Fast-Resume Audio Playback

ABSTRACT

A first zone player engages in synchronous playback of given audio content by obtaining the given audio content, generating and placing representative audio frames into a buffer, and transmitting the audio frames to a second zone player to play the given audio content in synchrony with the second zone player. After receiving a command to pause the synchronous playback, the first zone player prepares for a fast-resume by identifying a given audio frame and retaining at least some of the audio frames in the buffer for use during the fast-resume. The first zone player then initiates the fast-resume by determining a future resume time, transmitting an instruction to the second zone player to resume playback at the future resume time, and at the future resume time, resuming use of the audio frames in the buffer, starting with the given audio frame, to play the given audio content in synchrony.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 15/627,222 filed on Jun. 19, 2017, which is a continuation ofU.S. patent application Ser. No. 15/098,592 filed on Apr. 14, 2016 andissued on Jun. 20, 2017 as U.S. Pat. No. 9,684,485, which is acontinuation of U.S. application Ser. No. 14/042,301 filed on Sep. 30,2013 and issued on May 17, 2016 as U.S. Pat. No. 9,344,755, thedisclosures of which are explicitly incorporated by reference herein intheir entirety.

FIELD OF THE DISCLOSURE

The disclosure is related to consumer goods and, more particularly, tomethods, systems, products, features, services, and other items directedto media playback or some aspect thereof.

BACKGROUND

Digital music has become readily available due in part to thedevelopment of consumer level technology that has allowed people tolisten to digital music on a personal audio device. The consumer'sincreasing preference for digital audio has also resulted in theintegration of personal audio devices into PDAs, cellular phones, andother mobile devices. The portability of these mobile devices hasenabled people to take the music listening experience with them andoutside of the home. People have become able to consume digital music,like digital music files or even Internet radio, in the home through theuse of their computer or similar devices. Now there are many differentways to consume digital music, in addition to other digital contentincluding digital video and photos, stimulated in many ways byhigh-speed Internet access at home, mobile broadband Internet access,and the consumer's hunger for digital media.

Until recently, options for accessing and listening to digital audio inan out-loud setting were severely limited. In 2005, Sonos offered forsale its first digital audio system that enabled people to, among manyother things, access virtually unlimited sources of audio via one ormore networked connected zone players, dynamically group or ungroup zoneplayers upon command, wirelessly send the audio over a local networkamongst zone players, and play the digital audio out loud in synchrony.The Sonos system can be controlled by software applications downloadedto certain network capable, mobile devices and computers.

Given the insatiable appetite of consumers towards digital media, therecontinues to be a need to develop consumer technology thatrevolutionizes the way people access and consume digital media.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, aspects, and advantages of the presently disclosed technologymay be better understood with regard to the following description,appended claims, and accompanying drawings where:

FIG. 1 shows an example configuration in which certain embodiments maybe practiced;

FIG. 2A shows an illustration of an example zone player having abuilt-in amplifier and transducers;

FIG. 2B shows an illustration of an example zone player having abuilt-in amplifier and connected to external speakers;

FIG. 2C shows an illustration of an example zone player connected to anA/V receiver and speakers;

FIG. 3 shows an illustration of an example controller;

FIG. 4 shows an internal functional block diagram of an example zoneplayer;

FIG. 5 shows an internal functional block diagram of an examplecontroller;

FIG. 6 shows an example network for media content playback;

FIG. 7 shows an example ad-hoc playback network;

FIG. 8 shows a system including a plurality of networks including acloud-based network and at least one local playback network;

FIG. 9 is a block diagram of an example playback group including a groupcoordinator device and group member playback devices;

FIG. 10 is a flowchart illustrating an example process to begin, pause,and resume audio playback;

FIG. 11 is a flowchart illustrating an example process to pause playbackof audio for devices in a playback group;

FIG. 12 is a flowchart of an example process to fast-resume playback ofaudio after a pause of audio; and

FIG. 13 is a flowchart of an example process to fast-resume playback ofaudio after a pause of audio.

In addition, the drawings are for the purpose of illustrating exampleembodiments, but it is understood that the inventions are not limited tothe arrangements and instrumentality shown in the drawings.

DETAILED DESCRIPTION I. Overview

Embodiments of the methods and apparatus disclosed herein enable a userto fast-resume playback.

An example embodiment of a method implemented in accordance with thepresent disclosure includes transmitting, by a device to at least oneplayback device, a plurality of frames, each frame of the plurality offrames comprising audio information and playback timing information, theplayback timing information identifying a time to play the audioinformation of the respective frame, wherein the playback timinginformation comprises a time relative to a master clock; receiving, bythe device, a pause command, wherein the pause command indicates thatthe at least one playback device is to cease playback of the audioinformation; subsequent to receiving the pause command, receiving, bythe device, a resume command; based on the resume command, identifying,by the device, a range of frames previously transmitted by the device tothe at least one playback device, wherein the range of frames haveplayback timing information subsequent to a time that the devicereceived the pause command; and based on the resume command,instructing, by the device, the at least one playback device to (i)update the playback timing information in the range of frames, and (ii)play the audio information

In some embodiments, the instructing, by the device, the at least oneplayback device to update the playback timing information in the rangeof frames further comprises: instructing, by the device, the at leastone playback device to update the playback timing information in therange of frames when the range of frames is above a threshold number offrames.

In some embodiments, the audio information is received in a first audiostream by the device prior to transmission, by the device, to the atleast one playback device.

In some embodiments, the first audio stream is associated with a firstcryptographic key.

In some embodiments, the method further includes based on the pausecommand, terminating, by the device, reception of the first audiostream.

In some embodiments, the method further includes based on the resumecommand, initiating reception, by the device, of the audio informationin a second audio stream; determining, by the device, whether the secondaudio stream is associated with the first cryptographic key or with adifferent cryptographic key; and when the second audio stream isassociated with the different cryptographic key, providing, by thedevice, the different cryptographic key to the at least one playbackdevice.

In some embodiments, the device comprises a playback device, and whereinthe master clock comprises a clock associated with the device, and themethod further comprises: based on the resume command, playing, by thedevice, the audio information synchronously with the at least oneplayback device.

An example embodiment of a non-transitory computer-readable storagemedium implemented in accordance with the present disclosure includes aset of instructions for execution by a processor, the set ofinstructions, when executed cause a device to: transmit, to at least oneplayback device, a plurality of frames, each frame of the plurality offrames comprising audio information and playback timing information, theplayback timing information identifying a time to play the audioinformation of the respective frame, wherein the playback timinginformation comprises a time relative to a master clock; receive a pausecommand, wherein the pause command indicates that the at least oneplayback device is to cease playback of the audio information;subsequent to receiving the pause command, receive a resume command;based on the resume command, identify a range of frames previouslytransmitted by the device to the at least one playback device, whereinthe range of frames have playback timing information subsequent to atime that the device received the pause command; and based on the resumecommand, instruct the at least one playback device to (i) update theplayback timing information in the range of frames, and (ii) play theaudio information.

In some embodiments, the device instructs the at least one playbackdevice to update the playback timing information in the range of frameswhen the range of frames is above a threshold number of frames.

In some embodiments, the audio information is received in a first audiostream by the device prior to transmission, by the device, to the atleast one playback device.

In some embodiments, the first audio stream is associated with a firstcryptographic key.

In some embodiments, the instructions cause the device to terminate,based on the pause command, reception of the first audio stream.

In some embodiments, the instructions cause the device to, based on theresume command, initiate reception of the audio information in a secondaudio stream; determine whether the second audio stream is associatedwith the first cryptographic key or with a different cryptographic key;and when the second audio stream is associated with the differentcryptographic key, provide the different cryptographic key to the atleast one playback device.

In some embodiments, the device comprises a playback device, and whereinthe master clock comprises a clock associated with the device, and theinstructions cause the device to: based on the resume command, play theaudio information synchronously with the at least one playback device.

An example embodiment of a computing device implemented in accordancewith the present disclosure includes a processor, the computing devicearranged to: transmit, to at least one playback device, a plurality offrames, each frame of the plurality of frames comprising audioinformation and playback timing information, the playback timinginformation identifying a time to play the audio information of therespective frame, wherein the playback timing information comprises atime relative to a master clock; receive a pause command, wherein thepause command indicates that the at least one playback device is tocease playback of the audio information; subsequent to receiving thepause command, receive a resume command; based on the resume command,identify a range of frames previously transmitted by the device to theat least one playback device, wherein the range of frames have playbacktiming information subsequent to a time that the device received thepause command; and based on the resume command, instruct the at leastone playback device to (i) update the playback timing information in therange of frames, and (ii) play the audio information.

In some embodiments, the audio information is received in a first audiostream by the device prior to transmission, by the device, to the atleast one playback device.

In some embodiments, the first audio stream is associated with a firstcryptographic key.

In some embodiments, the device is further arranged to terminate, basedon the pause command, reception of the first audio stream. In someembodiments, the device is further arranged to: based on the resumecommand, initiate reception of the audio information in a second audiostream; determine whether the second audio stream is associated with thefirst cryptographic key or with a different cryptographic key; and whenthe second audio stream is associated with the different cryptographickey, provide the different cryptographic key to the at least oneplayback device.

In some embodiments, the device comprises a playback device, and whereinthe master clock comprises a clock associated with the device, andwherein the computing device is further arranged to: based on the resumecommand, play the audio information synchronously with the at least oneplayback device.

An example embodiment of a method implemented in accordance with thepresent disclosure includes transmitting, by a device to at least oneplayback device, a plurality of frames, each frame of the plurality offrames comprising audio information and playback timing information, theplayback timing information identifying a time to play the audioinformation of the respective frame, wherein the playback timinginformation comprises a time relative to a master clock; receiving, bythe device, a pause command, wherein the pause command indicates thatthe at least one playback device is to cease playback of the audioinformation; subsequent to receiving the pause command, receiving, bythe device, a resume command; based on the resume command, identifying,by the device, a range of frames maintained on the device, wherein therange of frames have playback timing information subsequent to a timethat the device received the pause command; and based on the resumecommand, (i) updating, by the device, the playback timing information inthe range of frames, and (ii) transmitting, by the device, updatedframes to the at least one playback device.

In some embodiments, the master clock comprises a clock associated withthe device.

In some embodiments, the audio information is received in a first audiostream by the device prior to transmission, by the device, to the atleast one playback device.

In some embodiments, the first audio stream is associated with a firstcryptographic key.

In some embodiments, the method further includes, based on the pausecommand, terminating, by the device, reception of the first audiostream. In some embodiments, the method further includes: based on theresume command, initiating reception, by the device, of the audioinformation in a second audio stream; determining, by the device,whether the second audio stream is associated with the firstcryptographic key or with a different cryptographic key; and when thesecond audio stream is associated with the different cryptographic key,providing, by the device, the different cryptographic key to the atleast one playback device.

In some embodiments, the device comprises a playback device, and themethod further includes, based on the resume command, playing, by thedevice, the audio information synchronously with the at least oneplayback device.

An example embodiment of a non-transitory computer-readable storagemedium implemented in accordance with the present disclosure includes aset of instructions for execution by a processor, the set ofinstructions, when executed cause a device to: transmit to at least oneplayback device, a plurality of frames, each frame of the plurality offrames comprising audio information and playback timing information, theplayback timing information identifying a time to play the audioinformation of the respective frame, wherein the playback timinginformation comprises a time relative to a master clock; receive a pausecommand, wherein the pause command indicates that the at least oneplayback device is to cease playback of the audio information;subsequent to receiving the pause command, receive a resume command;based on the resume command, identify a range of frames maintained onthe device, wherein the range of frames have playback timing informationsubsequent to a time that the device received the pause command; andbased on the resume command, (i) update the playback timing informationin the range of frames, and (ii) transmit updated frames to the at leastone playback device.

In some embodiments, the master clock comprises a clock associated withthe device.

In some embodiments, the audio information is received in a first audiostream by the device prior to transmission, by the device, to the atleast one playback device.

In some embodiments, the first audio stream is associated with a firstcryptographic key.

In some embodiments, the instructions further cause the device toterminate, based on the pause command, reception of the first audiostream.

In some embodiments, the instructions further cause the device to, basedon the resume command, initiate reception of the audio information in asecond audio stream; determine whether the second audio stream isassociated with the first cryptographic key or with a differentcryptographic key; and when the second audio stream is associated withthe different cryptographic key, provide the different cryptographic keyto the at least one playback device.

In some embodiments, the device comprises a playback device, and theinstructions further cause the device to: based on the resume command,play the audio information synchronously with the at least one playbackdevice.

An example embodiment of a computing device implemented in accordancewith the present disclosure includes a processor, the computing devicearranged to: transmit to at least one playback device, a plurality offrames, each frame of the plurality of frames comprising audioinformation and playback timing information, the playback timinginformation identifying a time to play the audio information of therespective frame, wherein the playback timing information comprises atime relative to a master clock; receive a pause command, wherein thepause command indicates that the at least one playback device is tocease playback of the audio information; subsequent to receiving thepause command, receive a resume command; based on the resume command,identify a range of frames maintained on the device, wherein the rangeof frames have playback timing information subsequent to a time that thedevice received the pause command; and based on the resume command, (i)update the playback timing information in the range of frames, and (ii)transmit updated frames to the at least one playback device.

In some embodiments, the master clock comprises a clock associated withthe device.

In some embodiments, the first audio stream is associated with a firstcryptographic key.

In some embodiments, the computing device is further arranged toterminate, based on the pause command, reception of the first audiostream.

In some embodiments, the computing device is further arranged to, basedon the resume command, initiate reception of the audio information in asecond audio stream; determine whether the second audio stream isassociated with the first cryptographic key or with a differentcryptographic key; and when the second audio stream is associated withthe different cryptographic key, provide the different cryptographic keyto the at least one playback device.

In some embodiments, the device comprises a playback device, and isfurther arranged to: based on the resume command, play the audioinformation synchronously with the at least one playback device.

An example embodiment of a method implemented in accordance with thepresent disclosure includes receiving, by a playback device from adevice, a plurality of frames, each frame of the plurality of framescomprising audio information and playback timing information, theplayback timing information identifying a time to play the audioinformation of the respective frame; receiving, by the playback device,a pause command, the pause command indicating that playback of the audioinformation is to be ceased; based on the received pause command,ceasing playback, by the playback device, of the audio information at aspecified pause time; subsequent to receiving the pause command,maintaining, by the playback device, at least a portion of the pluralityof frames received from the device having playback timing informationsubsequent to the specified pause time; subsequent to receiving thepause command, receiving, by the playback device, a command to resumeplayback; and based on the command to resume playback, (i) updating, bythe playback device, the playback timing information of the at least aportion of the plurality of frames received from the device, and (ii)playing, by the playback device, the audio information based on theupdated playback timing information.

In some embodiments, the specified pause time is included in the pausecommand.

In some embodiments, the command to resume playback identifies theplayback timing information of the at least a portion of the pluralityof frames received from the device.

In some embodiments, the command to resume playback further identifies aspecified time to resume playback.

In some embodiments, the playback device determines a time offsetbetween itself and the device.

In some embodiments, wherein the playback device updates timestampsbased on the offset.

In some embodiments, wherein the device comprises a second playbackdevice.

An example embodiment of a non-transitory computer-readable storagemedium implemented in accordance with the present disclosure includes aset of instructions for execution by a processor, the set ofinstructions, when executed cause a device to: receive from a device, aplurality of frames, each frame of the plurality of frames comprisingaudio information and playback timing information, the playback timinginformation identifying a time to play the audio information of therespective frame; receive a pause command, the pause command indicatingthat playback of the audio information is to be ceased; based on thereceived pause command, cease playback of the audio information at aspecified pause time; subsequent to receiving the pause command,maintain at least a portion of the plurality of frames received from thedevice having playback timing information subsequent to the specifiedpause time; subsequent to receiving the pause command, receive a commandto resume playback; and based on the command to resume playback, (i)update the playback timing information of the at least a portion of theplurality of frames received from the device, and (ii) play the audioinformation based on the updated playback timing information.

In some embodiments, the specified pause time is included in the pausecommand.

In some embodiments, the command to resume playback identifies theplayback timing information of the at least a portion of the pluralityof frames received from the device.

In some embodiments, the command to resume playback further identifies aspecified time to resume playback.

In some embodiments, the playback device determines a time offsetbetween itself and the device.

In some embodiments, the playback device updates timestamps based on theoffset.

In some embodiments, the device comprises a second playback device.

An example embodiment of a playback device implemented in accordancewith the present disclosure includes a processor, the playback devicearranged to: receive from a device, a plurality of frames, each frame ofthe plurality of frames comprising audio information and playback timinginformation, the playback timing information identifying a time to playthe audio information of the respective frame; receive a pause command,the pause command indicating that playback of the audio information isto be ceased; based on the received pause command, cease playback of theaudio information at a specified pause time; subsequent to receiving thepause command, maintain at least a portion of the plurality of framesreceived from the device having playback timing information subsequentto the specified pause time; subsequent to receiving the pause command,receive a command to resume playback; and based on the command to resumeplayback, (i) update the playback timing information of the at least aportion of the plurality of frames received from the device, and (ii)play the audio information based on the updated playback timinginformation.

In some embodiments, the specified pause time is included in the pausecommand.

In some embodiments, the command to resume playback identifies theplayback timing information of the at least a portion of the pluralityof frames received from the device.

In some embodiments, the command to resume playback further identifies aspecified time to resume playback.

In some embodiments, the playback device determines a time offsetbetween itself and the device.

In some embodiments, the playback device updates timestamps based on theoffset.

Other embodiments, as those discussed in the following and others as canbe appreciated by one having ordinary skill in the art are alsopossible.

II. Example Operating Environment

Referring now to the drawings, in which like numerals can refer to likeparts throughout the figures, FIG. 1 shows an example media systemconfiguration 100 in which one or more embodiments disclosed herein canbe practiced or implemented.

By way of illustration, the media system configuration 100 is associatedwith a home having multiple zones, though the home could have beenconfigured with only one zone. Additionally, one or more zones can beadded over time. Each zone may be assigned by a user to a different roomor space, such as, for example, an office, bathroom, bedroom, kitchen,dining room, family room, home theater room, utility or laundry room,and patio. A single zone might also include multiple rooms or spaces ifso configured. With respect to FIG. 1, one or more of zone players102-124 are shown in each respective zone. A zone player 102-124, alsoreferred to herein as a playback device, multimedia unit, speaker,player, and so on, provides audio, video, and/or audiovisual output. Acontroller 130 (e.g., shown in the kitchen for purposes of thisillustration) provides control to the media system configuration 100.Controller 130 may be fixed to a zone, or alternatively, mobile suchthat it can be moved about the zones. The media system configuration 100may also include more than one controller 130, and additionalcontrollers may be added to the system over time.

The media system configuration 100 illustrates an example whole housemedia system, though it is understood that the technology describedherein is not limited to, among other things, its particular place ofapplication or to an expansive system like a whole house media system100 of FIG. 1.

a. Example Zone Players

FIGS. 2A, 2B, and 2C show example types of zone players. Zone players200, 202, and 204 of FIGS. 2A, 2B, and 2C, respectively, can correspondto any of the zone players 102-124 of FIG. 1, for example. In someembodiments, audio is reproduced using only a single zone player, suchas by a full-range player. In some embodiments, audio is reproducedusing two or more zone players, such as by using a combination offull-range players or a combination of full-range and specializedplayers. In some embodiments, zone players 200-204 may also be referredto as a “smart speaker,” because they contain processing capabilitiesbeyond the reproduction of audio, more of which is described below.

FIG. 2A illustrates zone player 200 that includes sound producingequipment 208 capable of reproducing full-range sound. The sound maycome from an audio signal that is received and processed by zone player200 over a wired or wireless data network. Sound producing equipment 208includes one or more built-in amplifiers and one or more acoustictransducers (e.g., speakers). A built-in amplifier is described morebelow with respect to FIG. 4. A speaker or acoustic transducer caninclude, for example, any of a tweeter, a mid-range driver, a low-rangedriver, and a subwoofer. In some embodiments, zone player 200 can bestatically or dynamically configured to play stereophonic audio,monaural audio, or both. In some embodiments, zone player 200 may bedynamically configured to reproduce a subset of full-range sound, suchas when zone player 200 is grouped with other zone players to playstereophonic audio, monaural audio, and/or surround audio or when theaudio content received by zone player 200 is less than full-range.

FIG. 2B illustrates zone player 202 that includes a built-in amplifierto power a set of detached speakers 210. A detached speaker can include,for example, any type of loudspeaker. Zone player 202 may be configuredto power one, two, or more separate loudspeakers. Zone player 202 may beconfigured to communicate an audio signal (e.g., right and left channelaudio or more channels depending on its configuration) to the detachedspeakers 210 via a wired path.

FIG. 2C illustrates zone player 204 that does not include a built-inamplifier, but is configured to communicate an audio signal, receivedover a data network, to an audio (or “audio/video”) receiver 214 withbuilt-in amplification.

Referring back to FIG. 1, in some embodiments, one, some, or all of thezone players 102 to 124 can retrieve audio directly from a source. Forexample, a particular zone player in a zone or zone group may beassigned to a playback queue (or “queue”). The playback queue containsinformation corresponding to zero or more audio items for playback bythe associated zone or zone group. The playback queue may be stored inmemory on a zone player or some other designated device. Each itemcontained in the playback queue may comprise a uniform resourceidentifier (URI) or some other identifier that can be used by the zoneplayer(s) to seek out and/or retrieve the audio items from theidentified audio source(s). Depending on the item, the audio sourcemight be found on the Internet (e.g., the cloud), locally from anotherdevice over the data network 128 (described further below), from thecontroller 130, stored on the zone player itself, or from an audiosource communicating directly to the zone player. In some embodiments,the zone player can reproduce the audio itself (e.g., play the audio),send the audio to another zone player for reproduction, or both wherethe audio is reproduced by the zone player as well as one or moreadditional zone players (possibly in synchrony). In some embodiments,the zone player may play a first audio content (or alternatively, maynot play the content at all), while sending a second, different audiocontent to another zone player(s) for reproduction. To the user, eachitem in a playback queue is represented on an interface of a controllerby an element such as a track name, album name, playlist, or other someother representation. A user can populate the playback queue with audioitems of interest. The user may also modify and clear the playbackqueue, if so desired.

By way of illustration, SONOS, Inc. of Santa Barbara, Calif. presentlyoffers for sale zone players referred to as a “PLAY:5,” “PLAY:3,”“PLAYBAR,” “CONNECT:AMP,” “CONNECT,” and “SUB.” Any other past, present,and/or future zone players can additionally or alternatively be used toimplement the zone players of example embodiments disclosed herein.Additionally, it is understood that a zone player is not limited to theparticular examples illustrated in FIGS. 2A, 2B, and 2C or to the SONOSproduct offerings. For example, a zone player may include a wired orwireless headphone. In yet another example, a zone player might includea sound bar for television. In yet another example, a zone player mayinclude or interact with a docking station for an Apple IPOD™ or similardevice.

b. Example Controllers

FIG. 3 illustrates an example wireless controller 300 in docking station302. By way of illustration, controller 300 may correspond tocontrolling device 130 of FIG. 1. Docking station 302, if provided orused, may provide power to the controller 300 and additionally maycharge a battery of controller 300. In some embodiments, controller 300may be provided with a touch screen 304 that allows a user to interactthrough touch with the controller 300, for example, to retrieve andnavigate a playlist of audio items, control operations of one or morezone players, and provide overall control of the system configuration100. In other embodiments, other input mechanisms such as voice controlmay be used to interact with the controller 300. In certain embodiments,any number of controllers can be used to control the systemconfiguration 100. In some embodiments, there may be a limit set on thenumber of controllers that can control the system configuration 100. Thecontrollers might be wireless like wireless controller 300 or wired todata network 128.

In some embodiments, if more than one controller is used in system 100of FIG. 1, each controller may be coordinated to display common content,and may all be dynamically updated to indicate changes made to thesystem 100 from a single controller. Coordination can occur, forinstance, by a controller periodically requesting a state variabledirectly or indirectly from one or more of the zone players; the statevariable may provide information about system 100, such as current zonegroup configuration, what is playing in one or more zones, volumelevels, and other items of interest. The state variable may be passedaround on data network 128 between zone players (and controllers, if sodesired) as needed or as often as programmed.

In addition, an application running on any network-enabled portabledevice, such as an IPHONE™, IPAD™, ANDROID™ powered phone or tablet, orany other smart phone or network-enabled device can be used ascontroller 130. An application running on a laptop or desktop personalcomputer (PC) or Mac™ can also be used as controller 130. Suchcontrollers may connect to system 100 through an interface with datanetwork 128, a zone player, a wireless router, or using some otherconfigured connection path. Example controllers offered by Sonos, Inc.of Santa Barbara, Calif. include a “Controller 200,” “SONOS® CONTROL,”“SONOS® Controller for IPHONE™,” “SONOS® Controller for IPAD™,” “SONOS®Controller for ANDROID™,” “SONOS® Controller for MAC™ or PC.”

c. Example Data Connection

Zone players 102 to 124 of FIG. 1 are coupled directly or indirectly toa data network, such as data network 128. Controller 130 may also becoupled directly or indirectly to data network 128 or individual zoneplayers. Data network 128 is represented by an octagon in the figure tostand out from other representative components. While data network 128is shown in a single location, it is understood that such a network isdistributed in and around system 100. Particularly, data network 128 canbe a wired network, a wireless network, or a combination of both wiredand wireless networks. In some embodiments, one or more of the zoneplayers 102-124 are wirelessly coupled to data network 128 based on aproprietary mesh network. In some embodiments, one or more of the zoneplayers are coupled to data network 128 using a centralized access pointsuch as a wired or wireless router. In some embodiments, one or more ofthe zone players 102-124 are coupled via a wire to data network 128using Ethernet or similar technology. In addition to the one or morezone players 102-124 connecting to data network 128, data network 128can further allow access to a wide area network, such as the Internet.

In some embodiments, connecting any of the zone players 102-124, or someother connecting device, to a broadband router, can create data network128. Other zone players 102-124 can then be added wired or wirelessly tothe data network 128. For example, a zone player (e.g., any of zoneplayers 102-124) can be added to the system configuration 100 by simplypressing a button on the zone player itself (or perform some otheraction), which enables a connection to be made to data network 128. Thebroadband router can be connected to an Internet Service Provider (ISP),for example. The broadband router can be used to form another datanetwork within the system configuration 100, which can be used in otherapplications (e.g., web surfing). Data network 128 can also be used inother applications, if so programmed. An example, second network mayimplement SONOSNET™ protocol, developed by SONOS, Inc. of Santa Barbara.SONOSNET™ represents a secure, AES-encrypted, peer-to-peer wireless meshnetwork. Alternatively, in certain embodiments, the data network 128 isthe same network, such as a traditional wired or wireless network, usedfor other applications in the household.

d. Example Zone Configurations

A particular zone can contain one or more zone players. For example, thefamily room of FIG. 1 contains two zone players 106 and 108, while thekitchen is shown with one zone player 102. In another example, the hometheater room contains additional zone players to play audio from a 5.1channel or greater audio source (e.g., a movie encoded with 5.1 orgreater audio channels). In some embodiments, one can position a zoneplayer in a room or space and assign the zone player to a new orexisting zone via controller 130. As such, zones may be created,combined with another zone, removed, and given a specific name (e.g.,“Kitchen”), if so desired and programmed to do so with controller 130.Moreover, in some embodiments, zone configurations may be dynamicallychanged even after being configured using controller 130 or some othermechanism.

In some embodiments, a “bonded zone” is a zone that contains two or morezone players, such as the two zone players 106 and 108 in the familyroom, whereby the two zone players 106 and 108 can be configured to playthe same audio source in synchrony. In one example, the two zone players106 and 108 can be paired to play two separate sounds in left and rightchannels, for example. In other words, the stereo effects of a sound canbe reproduced or enhanced through the two zone players 106 and 108, onefor the left sound and the other for the right sound. In anotherexample, two or more zone players can be sonically consolidated to forma single, consolidated zone player. A consolidated zone player (thoughmade up of multiple, separate devices) can be configured to process andreproduce sound differently than an unconsolidated zone player or zoneplayers that are paired, because a consolidated zone player hasadditional speaker drivers from which sound can be passed. Theconsolidated zone player can further be paired with a single zone playeror yet another consolidated zone player. Each playback device of aconsolidated playback device can be set in a consolidated mode, forexample.

In certain embodiments, paired or consolidated zone players (alsoreferred to as “bonded zone players”) can play audio in synchrony withother zone players in the same or different zones.

According to some embodiments, one can continue to do any of: group,consolidate, and pair zone players, for example, until a desiredconfiguration is complete. The actions of grouping, consolidation, andpairing are preferably performed through a control interface, such asusing controller 130, and not by physically connecting and re-connectingspeaker wire, for example, to individual, discrete speakers to createdifferent configurations. As such, certain embodiments described hereinprovide a more flexible and dynamic platform through which soundreproduction can be offered to the end-user.

e. Example Audio Sources

In some embodiments, each zone can play from the same audio source asanother zone or each zone can play from a different audio source. Forexample, someone can be grilling on the patio and listening to jazzmusic via zone player 124, while someone is preparing food in thekitchen and listening to classical music via zone player 102. Further,someone can be in the office listening to the same jazz music via zoneplayer 110 that is playing on the patio via zone player 124. In someembodiments, the jazz music played via zone players 110 and 124 isplayed in synchrony. Synchronizing playback amongst zones allows forsomeone to pass through zones while seamlessly (or substantiallyseamlessly) listening to the audio. Further, zones can be put into a“party mode” such that all associated zones will play audio insynchrony.

Sources of audio content to be played by zone players 102-124 arenumerous. In some embodiments, audio on a zone player itself may beaccessed and played. In some embodiments, audio on a controller may beaccessed via the data network 128 and played. In some embodiments, musicfrom a personal library stored on a computer or networked-attachedstorage (NAS) may be accessed via the data network 128 and played. Insome embodiments, Internet radio stations, shows, and podcasts may beaccessed via the data network 128 and played. Music or cloud servicesthat let a user stream and/or download music and audio content may beaccessed via the data network 128 and played. Further, music may beobtained from traditional sources, such as a turntable or CD player, viaa line-in connection to a zone player, for example. Audio content mayalso be accessed using a different protocol, such as AIRPLAY™, which isa wireless technology by Apple, Inc., for example. Audio contentreceived from one or more sources can be shared amongst the zone players102 to 124 via data network 128 and/or controller 130. Theabove-disclosed sources of audio content are referred to herein asnetwork-based audio information sources. However, network-based audioinformation sources are not limited thereto.

In some embodiments, the example home theater zone players 116, 118, 120are coupled to an audio information source such as a television 132. Insome examples, the television 132 is used as a source of audio for thehome theater zone players 116, 118, 120, while in other examples audioinformation from the television 132 may be shared with any of the zoneplayers 102-124 in the audio system 100.

III. Example Zone Players

Referring now to FIG. 4, there is shown an example block diagram of azone player 400 in accordance with an embodiment. Zone player 400includes a network interface 402, a processor 408, a memory 410, anaudio processing component 412, one or more modules 414, an audioamplifier 416, and a speaker unit 418 coupled to the audio amplifier416. FIG. 2A shows an example illustration of such a zone player. Othertypes of zone players may not include the speaker unit 418 (e.g., suchas shown in FIG. 2B) or the audio amplifier 416 (e.g., such as shown inFIG. 2C). Further, it is contemplated that the zone player 400 can beintegrated into another component. For example, the zone player 400could be constructed as part of a television, lighting, or some otherdevice for indoor or outdoor use.

In some embodiments, network interface 402 facilitates a data flowbetween zone player 400 and other devices on a data network 128. In someembodiments, in addition to getting audio from another zone player ordevice on data network 128, zone player 400 may access audio directlyfrom the audio source, such as over a wide area network or on the localnetwork. In some embodiments, the network interface 402 can furtherhandle the address part of each packet so that it gets to the rightdestination or intercepts packets destined for the zone player 400.Accordingly, in certain embodiments, each of the packets includes anInternet Protocol (IP)-based source address as well as an IP-baseddestination address.

In some embodiments, network interface 402 can include one or both of awireless interface 404 and a wired interface 406. The wireless interface404, also referred to as a radio frequency (RF) interface, providesnetwork interface functions for the zone player 400 to wirelesslycommunicate with other devices (e.g., other zone player(s), speaker(s),receiver(s), component(s) associated with the data network 128, and soon) in accordance with a communication protocol (e.g., any wirelessstandard including IEEE 802.11a, 802.11b, 802.11g, 802.1 in, 802.15, 4Gmobile communication standard, and so on). Wireless interface 404 mayinclude one or more radios. To receive wireless signals and to providethe wireless signals to the wireless interface 404 and to transmitwireless signals, the zone player 400 includes one or more antennas 420.The wired interface 406 provides network interface functions for thezone player 400 to communicate over a wire with other devices inaccordance with a communication protocol (e.g., IEEE 802.3). In someembodiments, a zone player includes multiple wireless 404 interfaces. Insome embodiments, a zone player includes multiple wired 406 interfaces.In some embodiments, a zone player includes both of the interfaces 404and 406. In some embodiments, a zone player 400 includes only thewireless interface 404 or the wired interface 406.

In some embodiments, the processor 408 is a clock-driven electronicdevice that is configured to process input data according toinstructions stored in memory 410. The memory 410 is data storage thatcan be loaded with one or more software module(s) 414, which can beexecuted by the processor 408 to achieve certain tasks. In theillustrated embodiment, the memory 410 is a tangible machine-readablemedium storing instructions that can be executed by the processor 408.In some embodiments, a task might be for the zone player 400 to retrieveaudio data from another zone player or a device on a network (e.g.,using a uniform resource locator (URL) or some other identifier). Insome embodiments, a task may be for the zone player 400 to send audiodata to another zone player or device on a network. In some embodiments,a task may be for the zone player 400 to synchronize playback of audiowith one or more additional zone players. In some embodiments, a taskmay be to pair the zone player 400 with one or more zone players tocreate a multi-channel audio environment. Additional or alternativetasks can be achieved via the one or more software module(s) 414 and theprocessor 408.

The audio processing component 412 can include one or moredigital-to-analog converters (DAC), an audio preprocessing component, anaudio enhancement component or a digital signal processor, and so on. Insome embodiments, the audio processing component 412 may be part ofprocessor 408. In some embodiments, the audio that is retrieved via thenetwork interface 402 is processed and/or intentionally altered by theaudio processing component 412. Further, the audio processing component412 can produce analog audio signals. The processed analog audio signalsare then provided to the audio amplifier 416 for playback throughspeakers 418. In addition, the audio processing component 412 caninclude circuitry to process analog or digital signals as inputs to playfrom zone player 400, send to another zone player on a network, or bothplay and send to another zone player on the network. An example inputincludes a line-in connection (e.g., an auto-detecting 3.5 mm audioline-in connection).

The audio amplifier 416 is a device(s) that amplifies audio signals to alevel for driving one or more speakers 418. The one or more speakers 418can include an individual transducer (e.g., a “driver”) or a completespeaker system that includes an enclosure including one or more drivers.A particular driver can be a subwoofer (e.g., for low frequencies), amid-range driver (e.g., for middle frequencies), and a tweeter (e.g.,for high frequencies), for example. An enclosure can be sealed orported, for example. Each transducer may be driven by its own individualamplifier.

A commercial example, presently known as the PLAY:5™, is a zone playerwith a built-in amplifier and speakers that is capable of retrievingaudio directly from the source, such as on the Internet or on the localnetwork, for example. In particular, the PLAY:5™ is a five-amp,five-driver speaker system that includes two tweeters, two mid-rangedrivers, and one woofer. When playing audio content via the PLAY:5™, theleft audio data of a track is sent out of the left tweeter and leftmid-range driver, the right audio data of a track is sent out of theright tweeter and the right mid-range driver, and mono bass is sent outof the subwoofer. Further, both mid-range drivers and both tweeters havethe same equalization (or substantially the same equalization). That is,they are both sent the same frequencies but from different channels ofaudio. Audio from Internet radio stations, online music and videoservices, downloaded music, analog audio inputs, television, DVD, and soon, can be played from the PLAY:5™. IV. Example Controller

Referring now to FIG. 5, there is shown an example block diagram forcontroller 500, which can correspond to the controlling device 130 inFIG. 1. Controller 500 can be used to facilitate the control ofmulti-media applications, automation and others in a system. Inparticular, the controller 500 may be configured to facilitate aselection of a plurality of audio sources available on the network andenable control of one or more zone players (e.g., the zone players102-124 in FIG. 1) through a wireless or wired network interface 508.According to one embodiment, the wireless communications is based on anindustry standard (e.g., infrared, radio, wireless standards includingIEEE 802.11a, 802.11b, 802.11g, 802.11n, 802.15, 4G mobile communicationstandard, and so on). Further, when a particular audio is being accessedvia the controller 500 or being played via a zone player, a picture(e.g., album art) or any other data, associated with the audio and/oraudio source can be transmitted from a zone player or other electronicdevice to controller 500 for display.

Controller 500 is provided with a screen 502 and an input interface 514that allows a user to interact with the controller 500, for example, tonavigate a playlist of many multimedia items and to control operationsof one or more zone players. The screen 502 on the controller 500 can bean LCD screen, for example. The screen 502 communicates with and iscommanded by a screen driver 504 that is controlled by a microcontroller(e.g., a processor) 506. The memory 510 can be loaded with one or moreapplication modules 512 that can be executed by the microcontroller 506with or without a user input via the user interface 514 to achievecertain tasks. In some embodiments, an application module 512 isconfigured to facilitate grouping a number of selected zone players intoa zone group and synchronizing the zone players for audio playback. Insome embodiments, an application module 512 is configured to control theaudio sounds (e.g., volume) of the zone players in a zone group. Inoperation, when the microcontroller 506 executes one or more of theapplication modules 512, the screen driver 504 generates control signalsto drive the screen 502 to display an application specific userinterface accordingly.

The controller 500 includes a network interface 508 that facilitateswired or wireless communication with a zone player. In some embodiments,the commands such as volume control and audio playback synchronizationare sent via the network interface 508. In some embodiments, a savedzone group configuration is transmitted between a zone player and acontroller via the network interface 508. The controller 500 can controlone or more zone players, such as 102-124 of FIG. 1. There can be morethan one controller for a particular system, and each controller mayshare common information with another controller, or retrieve the commoninformation from a zone player, if such a zone player storesconfiguration data (e.g., such as a state variable). Further, acontroller can be integrated into a zone player.

It should be noted that other network-enabled devices such as anIPHONE™, IPAD™ or any other smart phone or network-enabled device (e.g.,a networked computer such as a PC or MAC™) can also be used as acontroller to interact or control zone players in a particularenvironment. In some embodiments, a software application or upgrade canbe downloaded onto a network-enabled device to perform the functionsdescribed herein.

In certain embodiments, a user can create a zone group (also referred toas a bonded zone) including at least two zone players from thecontroller 500. The zone players in the zone group can play audio in asynchronized fashion, such that all of the zone players in the zonegroup playback an identical audio source or a list of identical audiosources in a synchronized manner such that no (or substantially no)audible delays or hiccups are to be heard. Similarly, in someembodiments, when a user increases the audio volume of the group fromthe controller 500, the signals or data of increasing the audio volumefor the group are sent to one of the zone players and causes other zoneplayers in the group to be increased together in volume.

A user via the controller 500 can group zone players into a zone groupby activating a “Link Zones” or “Add Zone” soft button, or de-grouping azone group by activating an “Unlink Zones” or “Drop Zone” button. Forexample, one mechanism for ‘joining’ zone players together for audioplayback is to link a number of zone players together to form a group.To link a number of zone players together, a user can manually link eachzone player or room one after the other. For example, assume that thereis a multi-zone system that includes the following zones: Bathroom,Bedroom, Den, Dining Room, Family Room, and Foyer.

In certain embodiments, a user can link any number of the six zoneplayers, for example, by starting with a single zone and then manuallylinking each zone to that zone.

In certain embodiments, a set of zones can be dynamically linkedtogether using a command to create a zone scene or theme (subsequent tofirst creating the zone scene). For instance, a “Morning” zone scenecommand can link the Bedroom, Office, and Kitchen zones together in oneaction. Without this single command, the user would manually andindividually link each zone. The single command may include a mouseclick, a double mouse click, a button press, a gesture, or some otherprogrammed or learned action. Other kinds of zone scenes can beprogrammed or learned by the system over time.

In certain embodiments, a zone scene can be triggered based on time(e.g., an alarm clock function). For instance, a zone scene can be setto apply at 8:00 am. The system can link appropriate zonesautomatically, set specific music to play, and then stop the music aftera defined duration. Although any particular zone can be triggered to an“On” or “Off” state based on time, for example, a zone scene enables anyzone(s) linked to the scene to play a predefined audio (e.g., afavorable song, a predefined playlist) at a specific time and/or for aspecific duration. If, for any reason, the scheduled music failed to beplayed (e.g., an empty playlist, no connection to a share, failedUniversal Plug and Play (UPnP), no Internet connection for an InternetRadio station, and so on), a backup buzzer can be programmed to sound.The buzzer can include a sound file that is stored in a zone player, forexample.

V. Playback Queue

As discussed above, in some embodiments, a zone player may be assignedto or otherwise associated with a playback queue identifying zero ormore media items for playback by the zone player. The media itemsidentified in a playback queue may be represented to the user via aninterface on a controller. For instance, the representation may show theuser (or users if more than one controller is connected to the system)how the zone player is traversing the playback queue, such as byhighlighting the “now playing” item, graying out the previously playeditem(s), highlighting the to-be-played item(s), and so on.

In some embodiments, a single zone player is assigned to a playbackqueue. For example, zone player 114 in the bathroom of FIG. 1 may belinked or assigned to a “Bathroom” playback queue. In an embodiment, the“Bathroom” playback queue might have been established by the system as aresult of the user naming the zone player 114 to the bathroom. As such,contents populated and identified in the “Bathroom” playback queue canbe played via the zone player 114 (the bathroom zone).

In some embodiments, a zone or zone group is assigned to a playbackqueue. For example, zone players 106 and 108 in the family room of FIG.1 may be linked or assigned to a “Family room” playback queue. Inanother example, if family room and dining room zones were grouped, thenthe new group would be linked or assigned to a “family room+dining room”playback queue. In some embodiments, the family room+dining roomplayback queue would be established based upon the creation of thegroup. In some embodiments, upon establishment of the new group, thefamily room+dining room playback queue can automatically include thecontents of one (or both) of the playback queues associated with eitherthe family room or dining room or both. In one instance, if the userstarted with the family room and added the dining room, then thecontents of the family room playback queue would become the contents ofthe family room+dining room playback queue. In another instance, if theuser started with the family room and added the dining room, then thefamily room playback queue would be renamed to the family room+diningroom playback queue. If the new group was “ungrouped,” then the familyroom+dining room playback queue may be removed from the system and/orrenamed to one of the zones (e.g., renamed to “family room” or “diningroom”). After ungrouping, each of the family room and the dining roomwill be assigned to a separate playback queue. One or more of the zoneplayers in the zone or zone group may store in memory the associatedplayback queue.

As such, when zones or zone groups are “grouped” or “ungrouped”dynamically by the user via a controller, the system will, in someembodiments, establish or remove/rename playback queues respectively, aseach zone or zone group is to be assigned to a playback queue. In otherwords, the playback queue operates as a container that can be populatedwith media items for playback by the assigned zone. In some embodiments,the media items identified in a playback queue can be manipulated (e.g.,re-arranged, added to, deleted from, and so on).

By way of illustration, FIG. 6 shows an example network 600 for mediacontent playback. As shown, the example network 600 includes examplezone players 612 and 614, example audio sources 662 and 664, and examplemedia items 620. The example media items 620 may include playlist 622(e.g., a collection of audio tracks), track 624 (e.g., a song, an audiobook or chapter, a program, etc.), favorite Internet radio station 626(e.g., a stream of audio tracks), playlists 628 and 630, and album 632(e.g., an ordered collection of audio tracks). In one embodiment, thezone players 612 and 614 may be any of the zone players shown in FIGS.1, 2, and 4. For instance, zone players 612 and 614 may be the zoneplayers 106 and 108 in the Family Room.

In one example, the example audio sources 662 and 664, and example mediaitems 620 may be partially stored on a cloud network, discussed morebelow in connection to FIG. 8. In some cases, the portions of the audiosources 662, 664, and example media items 620 may be stored locally onone or both of the zone players 612 and 614. In one embodiment, playlist622, favorite Internet radio station 626, and playlist 630 may be storedlocally, and music track 624, playlist 628, and album 632 may be storedon the cloud network.

Each of the example media items 620 may be a list of media itemsplayable by a zone player(s). In one embodiment, the example media itemsmay be a collection of links or pointers (e.g., URI) to the underlyingdata for media items that are stored elsewhere, such as the audiosources 662 and 664. In another embodiment, the media items may includepointers to media content stored on the local zone player, another zoneplayer over a local network, or a controller device connected to thelocal network.

As shown, the example network 600 may also include an example queue 602associated with the zone player 612, and an example queue 604 associatedwith the zone player 614. Queue 606 may be associated with a group, whenin existence, comprising zone players 612 and 614. Queue 606 mightcomprise a new queue or exist as a renamed version of queue 602 or 604.In some embodiments, in a group, the zone players 612 and 614 would beassigned to queue 606 and queue 602 and 604 would not be available atthat time. In some embodiments, when the group is no longer inexistence, queue 606 is no longer available. Each zone player and eachcombination of zone players in a network of zone players, such as thoseshown in FIG. 1 or that of example zone players 612, 614, and examplecombination 616, may be uniquely assigned to a corresponding playbackqueue.

A playback queue, such as playback queues 602, 604, 606, may includeidentification of media content to be played by the corresponding zoneplayer or combination of zone players. As such, media items added to theplayback queue are to be played by the corresponding zone player orcombination of zone players. The zone player may be configured to playitems in the queue according to a specific order (such as an order inwhich the items were added), in a random order, or in some other order.

The playback queue may include a combination of playlists and othermedia items added to the queue. In one embodiment, the items in playbackqueue 602 to be played by the zone player 612 may include items from theaudio sources 662, 664, or any of the media items 622-632. The playbackqueue 602 may also include items stored locally on the zone player 612,or items accessible from the zone player 614. For instance, the playbackqueue 602 may include Internet radio 626 and album 632 items from audiosource 662, and items stored on the zone player 612.

When a media item is added to the queue via an interface of acontroller, a link to the item may be added to the queue. In a case ofadding a playlist to the queue, links to the media items in the playlistmay be provided to the queue. For example, the playback queue 602 mayinclude pointers from the Internet radio 626 and album 632, pointers toitems on the audio source 662, and pointers to items on the zone player612. In another case, a link to the playlist, for example, rather than alink to the media items in the playlist may be provided to the queue,and the zone player or combination of zone players may play the mediaitems in the playlist by accessing the media items via the playlist. Forexample, the album 632 may include pointers to items stored on audiosource 662. Rather than adding links to the items on audio source 662, alink to the album 632 may be added to the playback queue 602, such thatthe zone player 612 may play the items on the audio source 662 byaccessing the items via pointers in the album 632.

In some cases, contents as they exist at a point in time within aplayback queue may be stored as a playlist, and subsequently added tothe same queue later or added to another queue. For example, contents ofthe playback queue 602, at a particular point in time, may be saved as aplaylist, stored locally on the zone player 612 and/or on the cloudnetwork. The saved playlist may then be added to playback queue 604 tobe played by zone player 614.

VI. Example Ad-Hoc Network

Particular examples are now provided in connection with FIG. 7 todescribe, for purposes of illustration, certain embodiments to provideand facilitate connection to a playback network. FIG. 7 shows that thereare three zone players 702, 704 and 706 and a controller 708 that form anetwork branch that is also referred to as an Ad-Hoc network 710. Thenetwork 710 may be wireless, wired, or a combination of wired andwireless technologies. In general, an Ad-Hoc (or “spontaneous”) networkis a local area network or other small network in which there isgenerally no one access point for all traffic. With an establishedAd-Hoc network 710, the devices 702, 704, 706 and 708 can allcommunicate with each other in a “peer-to-peer” style of communication,for example. Furthermore, devices may join and/or leave from the network710, and the network 710 will automatically reconfigure itself withoutneeding the user to reconfigure the network 710. While an Ad-Hoc networkis referenced in FIG. 7, it is understood that a playback network may bebased on a type of network that is completely or partially differentfrom an Ad-Hoc network.

Using the Ad-Hoc network 710, the devices 702, 704, 706, and 708 canshare or exchange one or more audio sources and be dynamically grouped(or ungrouped) to play the same or different audio sources. For example,the devices 702 and 704 are grouped to playback one piece of music, andat the same time, the device 706 plays back another piece of music. Inother words, the devices 702, 704, 706 and 708, as shown in FIG. 7, forma HOUSEHOLD that distributes audio and/or reproduces sound. As usedherein, the term HOUSEHOLD (provided in uppercase letters todisambiguate from the user's domicile) is used to represent a collectionof networked devices that are cooperating to provide an application orservice. An instance of a HOUSEHOLD is identified with a household 700(or household identifier), though a HOUSEHOLD may be identified with adifferent area or place.

In certain embodiments, a household identifier (HHID) is a short stringor an identifier that is computer-generated to help ensure that it isunique. Accordingly, the network 710 can be characterized by a uniqueHHID and a unique set of configuration variables or parameters, such aschannels (e.g., respective frequency bands), service set identifier(SSID) (a sequence of alphanumeric characters as a name of a wirelessnetwork), and WEP keys (wired equivalent privacy) or other securitykeys. In certain embodiments, SSID is set to be the same as HHID.

In certain embodiments, each HOUSEHOLD includes two types of networknodes: a control point (CP) and a zone player (ZP). The control pointcontrols an overall network setup process and sequencing, including anautomatic generation of required network parameters (e.g., securitykeys). In an embodiment, the CP also provides the user with a HOUSEHOLDconfiguration user interface. The CP function can be provided by acomputer running a CP application module, or by a handheld controller(e.g., the controller 708) also running a CP application module, forexample. The zone player is any other device on the network that isplaced to participate in the automatic configuration process. The ZP, asa notation used herein, includes the controller 708 or a computingdevice, for example. In some embodiments, the functionality, or certainparts of the functionality, in both the CP and the ZP are combined at asingle node (e.g., a ZP contains a CP or vice-versa).

In certain embodiments, configuration of a HOUSEHOLD involves multipleCPs and ZPs that rendezvous and establish a known configuration suchthat they can use a standard networking protocol (e.g., IP over Wired orWireless Ethernet) for communication. In an embodiment, two types ofnetworks/protocols are employed: Ethernet 802.3 and Wireless 802.11g.Interconnections between a CP and a ZP can use either of thenetworks/protocols. A device in the system as a member of a HOUSEHOLDcan connect to both networks simultaneously.

In an environment that has both networks in use, it is assumed that atleast one device in a system is connected to both as a bridging device,thus providing bridging services between wired/wireless networks forothers. The zone player 706 in FIG. 7 is shown to be connected to bothnetworks, for example. The connectivity to the network 712 is based onEthernet and/or Wireless, while the connectivity to other devices 702,704 and 708 is based on Wireless and Ethernet if so desired.

It is understood, however, that in some embodiments each zone player706, 704, 702 may access the Internet when retrieving media from thecloud (e.g., the Internet) via the bridging device. For example, zoneplayer 702 may contain a uniform resource locator (URL) that specifiesan address to a particular audio track in the cloud. Using the URL, thezone player 702 may retrieve the audio track from the cloud, andultimately play the audio out of one or more zone players.

VII. Another Example System Configuration

FIG. 8 shows a system 800 including a plurality of interconnectednetworks including a cloud-based network and at least one local playbacknetwork. A local playback network includes a plurality of playbackdevices or players, though it is understood that the playback networkmay contain only one playback device. In certain embodiments, eachplayer has an ability to retrieve its content for playback. Control andcontent retrieval can be distributed or centralized, for example. Inputcan include streaming content provider input, third party applicationinput, mobile device input, user input, and/or other playback networkinput into the cloud for local distribution and playback.

As illustrated by the example system 800 of FIG. 8, a plurality ofcontent providers 820-850 can be connected to one or more local playbacknetworks 860-870 via a cloud and/or other network 810. Using the cloud810, a multimedia audio system server 820 (e.g., Sonos™), a mobiledevice 830, a third party application 840, a content provider 850 and soon can provide multimedia content (requested or otherwise) to localplayback networks 860, 870. Within each local playback network 860, 870,a controller 862, 872 and a playback device 864, 874 can be used toplayback audio content.

VIII. Reducing Time-to-Music for Grouped Playback Devices

Known methods to resume playback for grouped devices, such that resumingaudio playback is synchronous among the devices of the group, may incura delay (e.g., several seconds) from receipt of the resume command untilaudio is output. The delay resulting from known methods of resumingplayback may be larger for groups containing a large number of playbackdevices, because the known methods invalidate and/or remove the audiodata from the buffers (e.g., buffers from which audio is processed foractual playback) when playback is paused or stopped. Known methodsrequire refilling the buffers and re-transmitting the audio to allplayback devices in the group prior to resuming the audio.

In contrast to known methods of resuming playback, example methods andapparatus disclosed herein reduce the time-to-music (e.g., reduceddelays between a resume command and the actual output of sound) forgrouped players by using the audio data that was previously stored inthe buffers of a group coordinator device and/or of the playback devicesat the time the audio playback was paused or stopped.

FIG. 9 is a block diagram of an example playback group 900 including agroup coordinator (GC) device 902 and group member playback devices 904,906. The example group coordinator device 902 and/or the example groupmember playback devices 904, 906 may be implemented using multipledevices, such as, for example, the zone players 102-124 of FIG. 1, thezone players 200, 202, 204 of FIG. 2, the zone player 400 of FIG. 4, thezone players 612, 614 of FIG. 6, the zone players 702-706 of FIG. 7,and/or the playback devices 864, 874 of FIG. 8. The example playbackgroup 900 may include more or fewer group member playback devices 904,906. The playback group 900 may be the local playback networks 860, 870and/or the network 710.

Any of the example devices 902-906 may be the only playback device in anetwork or household playing a particular audio stream, or multiple onesof the devices 902-906 may be playing the stream simultaneously (e.g.,as a zone group, bonded zone, etc.). To facilitate these playbackscenarios, the playback process is divided between a channel source andone or more channel sink(s). The group coordinator 902 functions as thechannel source and retrieves an audio stream (e.g., from a contentprovider and/or a device on a local network) by setting up thecommunications resource(s), receiving the content data packets over aninterface (e.g., a wired interface, a wireless interface, etc.),determining a compression and/or coding format of the received content,handling metadata associated with the content, and/or otherwisepreparing the content for playback. The GC 902 also prepares the audioframes/packets/samples for transmission or provision to the channelsinks.

The playback devices 904, 906 function as channel sinks that decodeaudio data (received from the GC 902) into pulse-code modulation (PCM)samples, for example, and render the PCM samples (e.g., toelectrical/optical audio outputs and/or into actual sound via drivers).In some examples, the GC 902 is also a playback device (e.g., a channelsink). If content is playing on all of the example playback devices902-906, the channel source and channel sink processes execute in the GC902 and the remaining playback devices 904, 906 in the group are channelsinks. The playback devices 904, 906 are also referred to herein asgroup members (GMs) and/or grouped playback devices. When the GC 902receives audio data, the GC 902 provides the data to the playbackdevices 904, 906 in the playback group (including itself, ifapplicable). Each playback device 904, 906 runs the channel sink processand renders the audio in synchrony as described below.

The example GC 902 includes a transmit (Tx) buffer 908, an Rx buffer909, a clock 910, and a cryptographic key store 912. The example Txbuffer 908 temporarily stores packets and/or frames (e.g., data packetsof multiple audio frames) for transmission to the playback devices 904,906. The frames 914 stored in the Tx buffer 908 include audio data 916to be played. Each of the frames 914 stored in the Tx buffer 908 isassociated with playback timing information (e.g., a timestamp 918) thatindicates a time at which the audio data 916 in the respective packet orframe 914 is to be played by the devices 902-906. When stored in the Txbuffer 908, the timestamp 918 is referenced to the clock 910 of the GC902. When received at the playback devices 904, 906 as part of the frame914, the playback devices 904, 906 translate the example timestamp 918to reference the respective clocks of the playback devices 904, 906.Translation is based on an offset between the clock 910 and a clock 922determined during a synchronization routine, for example.

The example playback devices 904, 906 each include a receive (Rx) buffer920, a clock 922, and a cryptographic key store 924. The Rx buffer 920stores frames or packets received from the GC 902, such as commandpackets and/or frames of audio to be played.

The example clocks 910, 922 (also referred to herein as “codec clocks”)are derived from an oscillator that may run the audio codec in eachplayer. In certain examples, the clocks 910, 922 are not set to ameaningful time of day, but rather keep time (e.g., in seconds, inmicroseconds, in oscillator cycles, etc.) from when the GC 902 orplayback device 904, 906 is first powered on (e.g., booted up from apowered off state). Additionally or alternatively, the clocks 910, 922may synchronize to a designated value (e.g., 0). In this manner, theclocks 910, 922 function like an oscillator-triggered counter. Each ofthe clocks 910, 922 will likely return very different times even ifcalled simultaneously. To perform synchronized playback despitedifferent clock values, the playback devices 904, 906 maintainrespective clock offset time values from the clock 910 time value using,for example, simple network time protocol (SNTP).

The cryptographic key store 924 stores cryptographic keys received fromthe GC 902 and/or another source to be used for decrypting the audioframes. Some music sources provide encrypted audio information andcorresponding decryption keys. In situations in which the audio framesin the Rx buffer 920 are re-time stamped for subsequent playback, thecryptographic key store 924 may store the cryptographic keys received inassociation with the audio frames for subsequent decryption. Thecryptographic keys for audio stored in the Rx buffer 920 prior to apause command may be identified or marked separately from cryptographickeys for audio stored subsequent to the pause command and acorresponding resume command. The cryptographic keys in thecryptographic keys store 924 are linked to the audio frames (e.g., via apointer associated with (e.g., received with) the cryptographic keyand/or a pointer associated with (e.g., received with) the audioinformation. Each stream of audio information may be associated withtheir respective cryptographic keys at the devices 904, 906 so that thekeys are not discarded due to their age and/or so the audio informationcan be decrypted at a later time.

While an example manner of implementing the playback group 900 isillustrated in FIG. 9, one or more of the elements, processes and/ordevices illustrated in FIG. 9 may be combined, divided, re-arranged,omitted, eliminated and/or implemented in any other way. Further, theexample GC 902, the playback devices 904, 906, the example Tx buffers908, the example Rx buffers 909, 920, the example clocks 910, 922, theexample cryptographic key stores 912, 924, the example clock mapping 928and/or, more generally, the example playback group 900 may beimplemented by hardware, software, firmware and/or any combination ofhardware, software and/or firmware. Thus, for example, any of theexample GC 902, the playback devices 904, 906, the example Tx buffers908, the example Rx buffers 909, 920, the example clocks 910, 922, theexample cryptographic key stores 912, 924, the example clock mapping 928and/or, more generally, the example playback group 900 could beimplemented by one or more analog or digital circuit(s), logic circuits,programmable processor(s), application specific integrated circuit(s)(ASIC(s)), programmable logic device(s) (PLD(s)) and/or fieldprogrammable logic device(s) (FPLD(s)). When reading any of theapparatus or system claims of this patent to cover a purely softwareand/or firmware implementation, at least one of the example GC 902, theplayback devices 904, 906, the example Tx buffers 908, the example Rxbuffers 909, 920, the example clocks 910, 922, the example cryptographickey stores 912, 924, and/or the example clock mapping 928 is/are herebyexpressly defined to include a tangible computer readable storage deviceor storage disk such as a memory, a digital versatile disk (DVD), acompact disk (CD), a Blu-ray disk, etc. storing the software and/orfirmware. Further still, the example playback group 900 of FIG. 9 mayinclude one or more elements, processes and/or devices in addition to,or instead of, those illustrated in FIG. 9, and/or may include more thanone of any or all of the illustrated elements, processes and devices.

Flowcharts representative of example machine-readable instructions forimplementing the playback group 900 of FIG. 9 are shown in FIGS. 10-13.In this example, the machine readable instructions comprise program(s)for execution by a processor such as the processor 408 shown in theexample processor platform zone player 400 discussed above in connectionwith FIG. 4. The program(s) may be embodied in software stored on atangible computer readable storage medium such as a CD-ROM, a floppydisk, a hard drive, a digital versatile disk (DVD), a Blu-ray disk, or amemory associated with the processor 408, but the entire programs and/orparts thereof could alternatively be executed by a device other than theprocessor 408 and/or embodied in firmware or dedicated hardware.Further, although the example programs are described with reference tothe flowcharts illustrated in FIG. 4, many other methods of implementingthe example playback group 900 may alternatively be used. For example,the order of execution of the blocks may be changed, and/or some of theblocks described may be changed, eliminated, or combined.

As mentioned above, the example processes of FIGS. 10-13 may beimplemented using coded instructions (e.g., computer and/or machinereadable instructions) stored on a tangible computer readable storagemedium such as a hard disk drive, a flash memory, a read-only memory(ROM), a compact disk (CD), a digital versatile disk (DVD), a cache, arandom-access memory (RAM) and/or any other storage device or storagedisk in which information is stored for any duration (e.g., for extendedtime periods, permanently, for brief instances, for temporarilybuffering, and/or for caching of the information). As used herein, theterm tangible computer readable storage medium is expressly defined toinclude any type of computer readable storage device and/or storage diskand to exclude propagating signals and to exclude transmission media. Asused herein, “tangible computer readable storage medium” and “tangiblemachine readable storage medium” are used interchangeably. Additionallyor alternatively, the example processes of FIGS. 10-13 may beimplemented using coded instructions (e.g., computer and/or machinereadable instructions) stored on a non-transitory computer and/ormachine readable medium such as a hard disk drive, a flash memory, aread-only memory, a compact disk, a digital versatile disk, a cache, arandom-access memory and/or any other storage device or storage disk inwhich information is stored for any duration (e.g., for extended timeperiods, permanently, for brief instances, for temporarily buffering,and/or for caching of the information). As used herein, the termnon-transitory computer readable medium is expressly defined to includeany type of computer readable storage device and/or storage disk and toexclude propagating signals and to exclude transmission media. As usedherein, when the phrase “at least” is used as the transition term in apreamble of a claim, it is open-ended in the same manner as the term“comprising” is open ended.

FIG. 10 is a flowchart illustrating an example process 1000 to begin,pause, and resume audio playback. The example process 1000 of FIG. 10will be described with reference to the example playback group 900 andthe GC 902 of FIG. 9.

The example GC 902 of FIG. 9 determines whether a play command (e.g., acommand to playback audio) has been received (block 1002). For example,the GC 902 may receive the play command from a controller (e.g., thecontroller 500 of FIG. 5) via the wireless interface 404 or the wiredinterface 406 of FIG. 4. If a play command has not been received (block1002), control loops to block 1002 to await a play command.

When a play command is received (block 1002), the GC 902 beginsretrieving audio information (e.g., from an audio source) (block 1003).For example, the GC 902 may retrieve audio data from any of the sources662, 664 of FIG. 6 and/or the sources 810, 820, 830 of FIG. 8. The GC902 determines playback timing information (e.g., the timestamp 918 ofFIG. 9) associated with an audio frame (e.g., the audio frame 914 ofFIG. 9) (block 1004). For example, if the program is about to startplaying, the GC 902 estimates how far in the future the program shouldbe played. In estimating, the GC 902 may account for the time requiredto process and distribute the data. GC 902 may also account for the timerequired for the playback devices receiving the audio data (in thisexample, devices 904 and 906) to process the audio data for playing. TheGC 902 then reads the clock 910, adds the offset, and timestamps thepacket with the resulting sum of the time and offset (e.g., the“time-to-play” to packet of audio data). The audio frame 914 may beobtained from any audio source, such as the audio sources 810-850 ofFIG. 8, and contains audio information 916 to be rendered into sound bythe playback devices 902-906. The playback timing information (e.g.,timestamp 918) specifies a time at which the playback devices 902-906are to playback the audio information 916 in the audio frame 914. Thetimestamp 918 is referenced to the clock 910.

The GC 902 transmits the audio frame(s) 914, including the audioinformation 916 and the timestamp 918, to the playback devices 904, 906in the playback group 900 (e.g., via the antenna 420 and/or theinterfaces 402-406 of FIG. 4) (block 1006). As the audio is played, theGC 902 continues to stamp additional audio frames and/or packets withthe time(s) at which the audio should be played. The frames 914 areplaced into the Tx buffer 908. Data in the Tx buffer (e.g., the frames914) are transmitted from the GC 902 to the playback devices 904, 906wirelessly, for example. The playback devices 902-906 in the group 900play the audio in synchronization (block 1008). To playback the audio insynchrony, the playback devices 904, 906 determine respective timeoffsets between their respective clocks 922 and the clock 910 ofplayback device 902, and update the received timestamp 918 with theoffset. Additional examples of synchronized playback of audio bymultiple playback devices in a playback group are described in U.S. Pat.No. 8,234,395, for example. U.S. Pat. No. 8,234,395, also assigned toSONOS, Inc., is incorporated by reference herein in its entirety.

At block 1010, the GC 902 determines whether a pause command (e.g., acommand indicating that the devices 902-906 are to cease playback) hasbeen received. In the example of FIG. 10, the pause command isdistinguished from a “stop” command in that, upon resuming playbackafter a pause command, the devices 902-906 are to resume from the sametime in the audio. The GC 902 may receive the pause command from acontroller (e.g., the controller 500 of FIG. 5) via the wirelessinterface 404 or the wired interface 406 of FIG. 4. If a pause commandhas not been received (block 1010), control returns to block 1004 tocontinue determining playback timing information and transmitting audioframes to the GMs 904, 906.

When a pause command is received (block 1010), the example GC 902 pausesplayback of the audio by the group members (block 1012). In response tothe pause command, the GC 902 terminates reception of the audio stream.In the example of FIG. 9, the GC 902 prepares any untransmitted audioframes 914 in the Tx buffer 908 for a fast-resume, and commands the GMs904, 906 to cease playback of the audio in synchrony and prepare anyunplayed audio frames 926 in the Rx buffers 920 for a fast-resume. Anexample process to pause playback of audio is described below withreference to FIG. 11.

At block 1014, the GC 902 determines whether a resume command has beenreceived. The GC 902 may, for example, receive the resume command from acontroller (e.g., the controller 500 of FIG. 5) via the wirelessinterface 404 or the wired interface 406 of FIG. 4. If a resume commandis received (block 1014), the GC 902 fast-resumes playback of audio bythe playback group 900 (block 1016). Two example processes tofast-resume playback are described below with reference to FIG. 12 andFIG. 13.

If a resume command has not been received (block 1014), the GC 902determines whether another command has been received that causes achange in state of one or more of the devices 902-906 in the playbackgroup 900 (block 1018). For example, changes in the state of the devices902-906 may include a change in the playback group 900 (e.g., adding ordropping devices), a change in audio source, a seek command to adifferent location the audio track than the location at which the audiotrack was paused, a fast-forward and/or rewind command, or any otherstate-changing command that would invalidate the audio data in the Rxbuffers 920 and/or the Tx buffer 908. If no such state-changing commandhas been received (block 1018), control returns to block 1014 todetermine whether a resume command has been received. If astate-changing command has been received (block 1018), the devices902-906 in the playback group 900 reset a synchronization of theplayback group, after which a resume command may be treated as a playcommand (e.g., block 1002) that may include a particular location in anaudio track from which the audio is to resume. The example process 1000of FIG. 10 ends.

FIG. 11 is a flowchart illustrating an example process 1100 to pauseplayback of audio for devices (e.g., a GC 902 and GMs 904, 906) in aplayback group (e.g., the playback group 900 of FIG. 9). The exampleprocess 1100 of FIG. 11 may be performed to implement block 1012 of FIG.10 to pause playback of audio, for example. The example process 1100 ofFIG. 11 will be described with reference to the example playback group900 of FIG. 9 and the zone player 400 of FIG. 4.

The process 1100 of FIG. 11 begins when a pause command has beenreceived by a GC (e.g., the GC 902 of FIG. 9). The example GC 902determines a time location within an audio stream (e.g., 0:10 secondsfrom the beginning of an audio track) at which the pause command wasreceived (block 1102). In the example of FIG. 9, the GC 902 accesses aclock mapping 928 that maps a start time of the currently-playing audiotrack to the clock 910 of the GC 902, determines a current time of theclock 910, and calculates a time within the currently-playing audiotrack at which the pause command was received. For example, if the clockmapping 928 maps the start time of the audio track to clock time43565409 and the pause command was received at clock time 44095864, theGC 902 may determine the pause command to have been received X secondsinto the audio track based on the speed of the clock 910.

The GC 902 determines a most recent frame (or packet) played prior tothe pause command time location (determined in block 1102) based on thetimestamps of the audio frames (block 1104). The GC 902 retains theaudio frames 914 in the Tx buffer 908 until those audio frames have beenplayed (or the timestamp for the audio frames 914 has occurred on theclock 910). The GC 902 searches the audio frames 914 contained in the Txbuffer 908 to identify an audio frame having a highest timestamp that isless than the pause command time. The identified frame is the mostrecent audio frame played by the playback group 900 prior to receivingthe pause command. The GC 902 determines a next frame to be played afterthe pause command time location (determined in block 1102) based on thetimestamps of the frames (block 1106). The GC 902 searches the audioframes 914 contained in the Tx buffer 908 to identify an audio framehaving a lowest timestamp that is greater than the pause command time.The identified frame is the next audio frame to be played by theplayback group 900 upon receiving a resume command.

The GC 902 determines whether a most recent frame (block 1104) or a nextframe (block 1106) have been located (block 1108). If both the mostrecent frame and the next frame could not be located in the Tx buffer(block 1108), the example process 1100 ends because the GC 902 is notable to determine a location from which to resume. The example process1000 of FIG. 10 may also be aborted to re-synchronize the playback group900 for a subsequent play command. If the GC 902 locates the most recentframe (block 1104) or a next frame (block 1106), the GC 902 determines arelative track time (e.g., the point in time at which the audio trackwas paused with reference to the beginning of the currently-playingtrack) (block 1110). In contrast to the time location determined inblock 1102 (e.g., a time of the clock 910), the relative track time isdetermined and/or expressed as a time or distance from the start of theaudio track (e.g., 0:10 seconds, X clock cycles, Y audio frames, Z audiosamples, etc.).

The GC 902 commands the group playback devices 902-906 to immediatelycease playback (block 1112). For example, the GC 902 of FIG. 9 mayinsert a track boundary in the transmit data stream (e.g., aFRAME_TYPE_TRACK_BOUNDARY message), transmit the track boundary, andtransmit a message indicating that that the playback devices shouldcease playback at a certain time (the message could be aresynchronization message of the type described in U.S. Pat. No.8,234,395 discussed above). These messages cause the group of playbackdevices 904-906 to recognize and perform a synchronized stop in theaudio playback with the GC 902.

The GC 902 and the playback devices 904, 906 create respective staterecords to change their internal channel source states to “Paused”(block 1114). The state records may be used for, for example, subsequentprocessing of other commands from the user and/or to identify anappropriate action (e.g., fast-resume) upon receiving a resume command.

At block 1116, the GC 902 determines whether frame data in the Tx buffer908 is greater than a threshold amount of data. For example, the GC 902may determine whether at least a threshold number of frames of audio forthe paused audio track are stored in the Tx buffer 908. By determiningthat at least a threshold amount of audio is present in the Tx buffer908, the GC 902 may avoid a situation in which a fast-resume occurs andthe GC 902 subsequently runs out of audio to play before receivingadditional audio information to continue playing the audio track. Such alack of audio information following resuming playback can result inintermittent playback (e.g., starting, then stopping, then startingplayback again in a short period of time) that may be undesirable orirritating to the user. In some examples, the GC 902 may fill the Txbuffer 908 with additional audio frames for the paused audio track priorto making the determination in block 1116 or after making thedetermination in block 1116.

If the frame data in the Tx buffer 908 is greater than a thresholdamount (block 1116), the GC 902 may discard frames and/or packets in theTx buffer 908 having a relative timestamp prior to the relative tracktime (i.e., the time determined in block 1110) (block 1118).

At block 1120, the GC 902 determines a location in the audio track(e.g., a frame, a time) at which to resume playback upon receipt of aresume command (block 1120). In some examples, the frames are obtainedfrom an audio source in blocks or packets of multiple frames. In suchexamples, the GC 902 may determine a closest frame to the relative tracktime (e.g., a first block start location prior to or subsequent to therelative track time). In other examples, the audio frames may beindividually accessible by the GC 902, and the GC 902 determines thatthe next frame to be played upon a resume command is the next framedetermined from block 1106. Other examples are possible as well.

At block 1122, the GC 902 maintains the cryptographic parameters for theframes 914 in the Tx buffer 908. Some music sources may providedifferent cryptographic parameters for audio content following a resumeplayback command. In such a situation, frames 914 that are stored in theTx buffer 908 prior to the pause command may have differentcryptographic parameters than frames that are received upon resumingplayback. As such, the cryptographic parameters received after theresume command may not be usable to decrypt the frames 914 encryptedusing the prior cryptographic parameters. By maintaining thecryptographic parameters received prior to the pause commend, theplayers in group 900 can play back the buffered audio content even ifthe music source provides new cryptographic parameters after a resumecommand is received. Some audio sources do not use cryptography orprovide cryptographic parameters. In the event that the frames 914 arenot encrypted, the example GC 902 may omit or skip block 1122. After theexample process 1100 ends, control returns to block 1014 of FIG. 10.

Returning to FIG. 10, after a resume command is received, the processadvances to block 1016. As shown, at block 1016, the group membersfast-resume the playback of audio. FIG. 12 is a flowchart of an exampleprocess 1200 that may be used to implement block 1016 of FIG. 10. FIG.12 will also be described with reference to the example playback group900 of FIG. 9. In the example process 1200 of FIG. 12, the GC 902 ofFIG. 9 re-timestamps each of the frames 914 in the Tx buffer 908 withnew timestamps for synchronized playback by the devices 902-906 in theplayback group and transmits the re-time stamped audio frames to thedevices 904, 906. In contrast to known methods of resuming synchronizedaudio playback from a paused state, the process 1200 of FIG. 12leverages the portions of the audio that were previously stored forplayback so that a delay in receiving audio from an audio source doesnot delay the resumption of playback.

The example process 1200 begins when a resume command is received (e.g.,at the GC 902 of FIG. 9). The example GC 902 selects a timestamp (e.g.,referenced to the clock 910) occurring in the future to be a new starttime for the frames 914 maintained in the Tx buffer 908 (block 1202).The timestamp selection may be performed in a manner similar to thetimestamp selection that occurs when playback is initiated, and is usedto synchronize playback of the audio by multiple devices 902-906.

Blocks 1204-1210 may operate as a logical “FOR” loop by iterating theblocks 1204-1210 until a condition is met or finished. The example block1204 iterates execution of the FOR loop 1204-1210 for each frame 914present in the Tx buffer 908. During execution of one iteration of theFOR loop 1204-1210, a frame 914 is considered to be selected. At block1206, the GC 902 finds a time difference between a frame occurring priorto receiving the pause command (e.g., the most recent frame played(discussed in block 1104) or the next frame to be played (discussed inblock 1106)) and the selected current frame. For example, the GC 902 maycompare a timestamp of the frame occurring immediately prior to thepause command to a timestamp of the selected current frame to determinea time difference. The GC 902 adds the time difference (determined inblock 1206) to the new start time (determined in block 1202) totimestamp the selected current frame with a new frame time (block 1208).For example, the GC 902 may modify the timestamp 918 of the selectedcurrent frame 914 with an updated time using new start time and theoffset between the timestamp 918 of the selected current frame 914 andthe relative track time. The GC 902 then returns to the beginning of theFOR loop 1204-1210 or ends the FOR loop 1204-1210 (block 1210) based onwhether all of the frames 914 in the Tx buffer 908 have been processedvia the FOR loop 1204-1210.

After processing each of the frames 914 via the FOR loop 1204-1210, theGC 902 transmits the newly time-stamped audio frames 914 in the Txbuffer 908 to the playback devices 904-906 in the playback group 900(block 1212). For example, the frame 914 having the lowest timestamp 918may be transmitted first. It should be understood that there are severalmethods by which GC could transmit the frames 914. For example, the GC902 could transmit each frame after the frame has been processed andwhile the GC 902 is processing additional frames. As another example theGC 902 could transmit all of the frames after they have been updated.

At block 1214, the playback devices 904, 906 receive the frames, andupdate each frame's timestamp 918 to a local timestamp 930 based on therespective clocks 922 of the playback devices 904, 906. When the valuesof the clocks 922 reach the value of the local timestamp 930 (block1216), the playback devices 904, 906 playback the audio information inthe corresponding frame 926 (block 1218). If the GC 902 is also a groupmember, it may playback the audio synchronously with playback devices904-906.

After the GC 902 finishes transmitting the updated frames to playbackdevices 902, 904, the example process 1200 may end and control returnsto block 1003 of FIG. 10 to continue determining playback timinginformation. After transmitting the previous audio frames, the GC 902begins time stamping and transmitting frames containing data receivedfrom the audio source. In some examples, the GC 902 may begin timestamping and transmitting frames to replace corresponding ones of theprevious frames (e.g., previous frames having the same audioinformation) if the audio information is received from the audio sourceprior to the previous frames being exhausted. In some other examples,the GC 902 may request to receive audio information from the audiosource beginning with audio information immediately following the audioinformation in the previous frames to avoid processing duplicate audiodata and/or wasting processing and/or network resources.

As discussed above, some audio sources may change cryptographicparameters for audio content provided to the GC 902 subsequent toreceipt of the resume command. In this case, the GC 902 may receiveupdated cryptographic parameters from the audio source and may transmitthose parameters to playback devices 904, 906 for use in decryptingaudio. As another example, playback devices 904, 906 could independentlydetermine that the cryptographic parameters associated with the audiohave changed, and may request new parameters from the audio source (orfrom the GC 902) directly.

FIG. 13 is a flowchart of another example process 1300 for fast-resumingplayback of audio after a pause of audio. The example process 1300 ofFIG. 13 may be used to implement block 1016 of FIG. 10, for example, andwill be described with reference to the example playback group 900 ofFIG. 9. In the example process 1300 of FIG. 13, the playback devices904, 906 of FIG. 9 re-timestamp each of the frames 926 in the Rx buffer920 using a new timestamps determined by the GC 902 for synchronizedplayback by the devices 902-906 in the playback group 900. In contrastwith the example process 1200 of FIG. 12 in which the GC 902 retransmitsaudio data, the playback devices 904, 906 in process 1300 maintain theaudio data subsequent to receipt of the pause command, and re-timestampthe data subsequent to receipt of a resume command.

The example process 1300 begins when a resume command is received (e.g.,at the GC 902 of FIG. 9). The example GC 902 selects a timestamp (e.g.,referenced to the clock 910) occurring in the future to be a new starttime for the frames 914 in the Tx buffer 908 (block 1302). The timestampselection may be performed in a manner similar to the timestampselection described above, and is used to synchronize playback of theaudio by multiple devices 902-906.

The GC 902 constructs a command packet specifying the new start time anda range of frames to be adjusted (block 1304). The range of frames inthe command packet is referenced to the clock 910 of the GC 902 and mayinclude, for example, a start timestamp and an end timestamp of therange, where any frame having a timestamp falling between the timestampsis considered to be within the range. The range of frames may bedetermined based on, for example, the timestamps 918 of the packets 914present in the Tx buffer 908 (e.g., audio frames 914 present in the Txbuffer 908 subsequent to performance of the process 1100 of FIG. 11).The GC 902 transmits the command packet to the playback devices 904, 906in the playback group 900 (block 1306) and the playback devices 904, 906receive the command packet (block 1308).

The example playback device 904, 906 calculates a local new start timefrom the new start time received in the command packet (block 1310). Thelocal new start time is determined using an offset between the clocks910 and 922 determined by the playback device 904, 906 and results in alocal new start time equivalent to the received new start time within anacceptable margin of error.

Blocks 1312-1318 are similar to blocks 1204-1210 of FIG. 12 and operateas a logical “FOR” loop by iterating the blocks 1312-1318 until acondition is met or finished. The example block 1312 iterates executionof the FOR loop 1312-1318 for each frame 926 present in the Rx buffer920 of FIG. 9. During execution of one iteration of the FOR loop1312-1318, a frame 926 is considered to be selected. The playback device904, 906 finds a time difference between a frame occurring prior toreceiving the pause command (e.g., the most recent frame played(discussed in block 1104) or the next frame to be played (discussed inblock 1106), and the selected current frame (block 1314). For example,the playback device 904, 906 may compare a timestamp of the frameoccurring immediately prior to the pause command to a timestamp 930 ofthe selected current frame 926 (e.g., referenced to the clock 922) todetermine a difference (e.g., in counts or cycles of the clock 922). Theplayback device 904, 906 adds the time difference (determined in block1314) to the new local start time (determined in block 1310) totimestamp the selected current frame 926 with a new local frametimestamp (block 1316). For example, the playback device 904, 906modifies the timestamp 930 of the selected current frame 914 with anupdated local time using the new local start time and the offset betweenthe timestamp 930 of the selected current frame 926 and the relativetrack time. The playback device 904, 906 then returns to the beginningof the FOR loop 1312-1318 or ends the FOR loop 1312-1318 (block 1318)based on whether all of the frames 926 in the Rx buffer 920 have beenprocessed via the FOR loop 1312-1318.

After processing each of the frames 926 via the FOR loop 1312-1318, theplayback device 904 determines whether the local new start time has beenreached by the clock 922 (block 1320). If the local new start time hasnot yet been reached (block 1320), control loops to block 1320 tocontinue waiting for the local new start time to occur.

When the local new start time is reached (block 1320), the playbackdevice 904, 906 plays the audio in synchrony with other playback devices(including the GC 902) in the playback group 900 according to thetimestamps 930 (block 1322).

As noted above, while playing the audio (block 1322), the exampleplayback device 904, 906 may decrypt the audio frames 904 using acryptographic key. For the frames within the range of frames (block1304), the playback device 904 may use a cryptographic key receivedprior to the pause command. However, frames subsequent to the range offrames may require a different cryptographic key for successfuldecryption. The playback device 904, 906 may obtain new cryptographicparameters either from the GC 902 or from the audio source directly.

While blocks 1308-1322 are described above with reference to theplayback device 904, the example blocks 1308-1322 may additionally oralternatively be performed by the playback device 906 (e.g.,concurrently performed by the playback devices 904, 906).

The example process 1300 may end and control returns to block 1003 ofFIG. 10 to continue receiving audio information and determining playbacktiming information. After transmitting the previous audio frames, the GC902 begins time stamping and transmitting frames containing datareceived from the audio source. In some examples, the GC 902 may begintime stamping and transmitting frames to replace corresponding ones ofthe previous frames (e.g., previous frames having the same audioinformation) if the audio information is received from the audio sourceprior to the previous frames being exhausted. In some other examples,the GC 902 may request to receive audio information from the audiosource beginning with audio information immediately following the audioinformation in the previous frames to avoid processing duplicate audiodata and/or wasting processing and/or network resources.

IX. Conclusion

The descriptions above disclose various example systems, methods,apparatus, and articles of manufacture including, among othercomponents, firmware and/or software executed on hardware. However, suchexamples are merely illustrative and should not be considered aslimiting. For example, it is contemplated that any or all of thesefirmware, hardware, and/or software components can be embodiedexclusively in hardware, exclusively in software, exclusively infirmware, or in any combination of hardware, software, and/or firmware.Accordingly, while the following describes example systems, methods,apparatus, and/or articles of manufacture, the examples provided are notthe only way(s) to implement such systems, methods, apparatus, and/orarticles of manufacture.

As suggested above, the present application involves providing methodsand apparatus to fast-resume audio playback.

In one aspect, a first method is provided. The first method involvestransmitting, by a device to at least one playback device, a pluralityof frames, each frame of the plurality of frames comprising audioinformation and playback timing information, the playback timinginformation identifying a time to play the audio information of therespective frame, wherein the playback timing information comprises atime relative to a master clock; receiving, by the device, a pausecommand, wherein the pause command indicates that the at least oneplayback device should cease playback of the audio information;subsequent to receiving the pause command, receiving, by the device, aresume command; based on the resume command, identifying, by the device,a range of frames previously transmitted by the device to the at leastone playback device, wherein the range of frames have playback timinginformation subsequent to a time that the device received the pausecommand; based on the resume command, instructing, by the device, the atleast one playback device to (i) update the playback timing informationin the range of frames, and (ii) play the audio information.

In another aspect, a second method is provided. The second methodinvolves transmitting, by a device to at least one playback device, aplurality of frames, each frame of the plurality of frames comprisingaudio information and playback timing information, the playback timinginformation identifying a time to play the audio information of therespective frame, wherein the playback timing information comprises atime relative to a master clock; receiving, by the device, a pausecommand, wherein the pause command indicates that the at least oneplayback device should cease playback of the audio information;subsequent to receiving the pause command, receiving, by the device, aresume command; based on the resume command, identifying, by the device,a range of frames maintained on the device, wherein the range of frameshave playback timing information subsequent to a time that the devicereceived the pause command; and based on the resume command, (i)updating, by the device, the playback timing information in the range offrames, and (ii) transmitting, by the device, the updated frames to theat least one playback device.

In yet another aspect, a third method is provided. The third methodinvolves receiving, by a playback device from a device, a plurality offrames, each frame of the plurality of frames comprising audioinformation and playback timing information, the playback timinginformation identifying a time to play the audio information of therespective frame; receiving, by the playback device, a pause command,the pause command indicating that playback of the audio informationshould be ceased; based on the received pause command, ceasing playback,by the playback device, of the audio information at a specified pausetime; subsequent to receiving the pause command, maintaining, by theplayback device, at least a portion of the plurality of frames receivedfrom the device having playback timing information subsequent to thespecified pause time; subsequent to receiving the pause command,receiving, by the playback device, a command to resume playback; andbased on the command to resume playback, (i) updating, by the playbackdevice, the playback timing information of the at least a portion of theplurality of frames received from the device, and (ii) playing, by theplayback device, the audio information based on the updated playbacktiming information.

In a further aspect, a first non-transitory computer readable mediumhaving instructions stored thereon is provided. The instructions areexecutable by a computing device to cause the computing device to atleast transmit, to at least one playback device, a plurality of frames,each frame of the plurality of frames comprising audio information andplayback timing information, the playback timing information identifyinga time to play the audio information of the respective frame, whereinthe playback timing information comprises a time relative to a masterclock; receive a pause command, wherein the pause command indicates thatthe at least one playback device should cease playback of the audioinformation; subsequent to receiving the pause command, receive a resumecommand; based on the resume command, identify a range of framespreviously transmitted by the device to the at least one playbackdevice, wherein the range of frames have playback timing informationsubsequent to a time that the device received the pause command; andbased on the resume command, instruct the at least one playback deviceto (i) update the playback timing information in the range of frames,and (ii) play the audio information.

In another aspect, a second non-transitory computer readable mediumhaving instructions stored thereon is provided. The instructions areexecutable by a computing device to cause the computing device to atleast transmit to at least one playback device, a plurality of frames,each frame of the plurality of frames comprising audio information andplayback timing information, the playback timing information identifyinga time to play the audio information of the respective frame, whereinthe playback timing information comprises a time relative to a masterclock; receive a pause command, wherein the pause command indicates thatthe at least one playback device should cease playback of the audioinformation; subsequent to receiving the pause command, receive a resumecommand; based on the resume command, identify a range of framesmaintained on the device, wherein the range of frames have playbacktiming information subsequent to a time that the device received thepause command; and based on the resume command, (i) update the playbacktiming information in the range of frames, and (ii) transmit the updatedframes to the at least one playback device.

In yet another aspect, a third non-transitory computer readable mediumhaving instructions stored thereon is provided. The instructions areexecutable by a computing device to cause the computing device to atleast receive from a device, a plurality of frames, each frame of theplurality of frames comprising audio information and playback timinginformation, the playback timing information identifying a time to playthe audio information of the respective frame; receive a pause command,the pause command indicating that playback of the audio informationshould be ceased; based on the received pause command, cease playback ofthe audio information at a specified pause time; subsequent to receivingthe pause command, maintain at least a portion of the plurality offrames received from the device having playback timing informationsubsequent to the specified pause time; subsequent to receiving thepause command, receive a command to resume playback; and based on thecommand to resume playback, (i) update the playback timing informationof the at least a portion of the plurality of frames received from thedevice, and (ii) play the audio information based on the updatedplayback timing information.

In a further aspect, a first computing device includes a processor. Thefirst device is arranged to transmit, to at least one playback device, aplurality of frames, each frame of the plurality of frames comprisingaudio information and playback timing information, the playback timinginformation identifying a time to play the audio information of therespective frame, wherein the playback timing information comprises atime relative to a master clock; receive a pause command, wherein thepause command indicates that the at least one playback device shouldcease playback of the audio information; subsequent to receiving thepause command, receive a resume command; based on the resume command,identify a range of frames previously transmitted by the device to theat least one playback device, wherein the range of frames have playbacktiming information subsequent to a time that the device received thepause command; and based on the resume command, instruct the at leastone playback device to (i) update the playback timing information in therange of frames, and (ii) play the audio information.

In another aspect, a second computing device includes a processor. Thesecond device is arranged to transmit to at least one playback device, aplurality of frames, each frame of the plurality of frames comprisingaudio information and playback timing information, the playback timinginformation identifying a time to play the audio information of therespective frame, wherein the playback timing information comprises atime relative to a master clock; receive a pause command, wherein thepause command indicates that the at least one playback device shouldcease playback of the audio information; subsequent to receiving thepause command, receive a resume command; based on the resume command,identify a range of frames maintained on the device, wherein the rangeof frames have playback timing information subsequent to a time that thedevice received the pause command; and based on the resume command, (i)update the playback timing information in the range of frames, and (ii)transmit the updated frames to the at least one playback device.

In yet another aspect, a playback device includes a processor. Theplayback device is arranged to receive from a device, a plurality offrames, each frame of the plurality of frames comprising audioinformation and playback timing information, the playback timinginformation identifying a time to play the audio information of therespective frame; receive a pause command, the pause command indicatingthat playback of the audio information should be ceased; based on thereceived pause command, cease playback of the audio information at aspecified pause time; subsequent to receiving the pause command,maintain at least a portion of the plurality of frames received from thedevice having playback timing information subsequent to the specifiedpause time; subsequent to receiving the pause command, receive a commandto resume playback; and based on the command to resume playback, (i)update the playback timing information of the at least a portion of theplurality of frames received from the device, and (ii) play the audioinformation based on the updated playback timing information.

Additionally, references herein to “embodiment” means that a particularfeature, structure, or characteristic described in connection with theembodiment can be included in at least one example embodiment of theinvention. The appearances of this phrase in various places in thespecification are not necessarily all referring to the same embodiment,nor are separate or alternative embodiments mutually exclusive of otherembodiments. As such, the embodiments described herein, explicitly andimplicitly understood by one skilled in the art, can be combined withother embodiments.

The specification is presented largely in terms of illustrativeenvironments, systems, procedures, steps, logic blocks, processing, andother symbolic representations that directly or indirectly resemble theoperations of data processing devices coupled to networks. These processdescriptions and representations are typically used by those skilled inthe art to most effectively convey the substance of their work to othersskilled in the art. Numerous specific details are set forth to provide athorough understanding of the present disclosure. However, it isunderstood to those skilled in the art that certain embodiments of thepresent disclosure can be practiced without certain, specific details.In other instances, well known methods, procedures, components, andcircuitry have not been described in detail to avoid unnecessarilyobscuring aspects of the embodiments. Accordingly, the scope of thepresent disclosure is defined by the appended claims rather than theforgoing description of embodiments.

When any of the appended claims are read to cover a purely softwareand/or firmware implementation, at least one of the elements in at leastone example is hereby expressly defined to include a tangible mediumsuch as a memory, DVD, CD, Blu-ray, and so on, storing the softwareand/or firmware.

We claim:
 1. A first zone player comprising: a processor; anon-transitory computer-readable medium; and program instructions storedon the tangible, non-transitory computer-readable medium that areexecutable by the at least one processor such that the first zone playeris configured to: engage in synchronous playback of given audio contentas part of a group that includes at least a second zone player, whereinengaging in the synchronous playback of given audio content as part ofthe group involves: obtaining the given audio content from an audiosource; generating audio frames that are representative of the givenaudio content; placing the audio frames into a buffer of the first zoneplayer; transmitting the audio frames in the buffer to the second zoneplayer; and using the audio frames in the buffer to play the given audiocontent in synchrony with the second zone player; while engaging in thesynchronous playback of the given audio content as part of the group,receive a command to pause the synchronous playback of the given audiocontent; after receiving the command to pause the synchronous playbackof the given audio content, prepare for a fast-resume of the synchronousplayback of the given audio content, wherein preparing for thefast-resume of the synchronous playback of the given audio contentinvolves: identifying a given audio frame in the buffer at which tobegin the fast-resume; sending an instruction to the second zone playerto cease playback of the given audio content and prepare for thefast-resume; and ceasing use of the audio frames in the buffer to playthe given audio content while retaining at least some of the audioframes in the buffer for use during the fast-resume; thereafter receivea command to resume playback of the given audio content; and afterreceiving the command to resume playback of the given audio content,initiate the fast-resume of the synchronous playback of the given audiocontent, wherein initiating the fast-resume of the synchronous playbackof the given audio content involves: determining a future resume time atwhich the first and second zone players are to resume the synchronousplayback of the given audio content; transmitting an instruction to thesecond zone player to resume playback of the given audio content at thefuture resume time; and at the future resume time, resuming use of theaudio frames in the buffer, starting with the given audio frame, to playthe given audio content in synchrony with the second zone player.
 2. Thefirst zone player of claim 1, wherein identifying the given audio framein the buffer at which to begin the fast-resume comprises: determining atime within the given audio content that corresponds to when the commandto pause the synchronous playback of the given audio content wasreceived; and identifying whichever audio frame in the buffercorresponds to a time within the given audio content that is closest tothe determined time within the given audio content.
 3. The first zoneplayer of claim 1, wherein identifying the given audio frame in thebuffer at which to begin the fast-resume comprises: identifyingwhichever audio frame in the buffer was scheduled to be played next whenthe command to pause the synchronous playback of the given audio contentwas received.
 4. The first zone player of claim 1, wherein the at leastsome of the audio frames that are retained in the buffer of the firstzone player comprise at least the given audio frame and any audio framein the buffer subsequent to the given audio frame.
 5. The first zoneplayer of claim 1, wherein retaining the at least some of the audioframes in the buffer for use during the fast-resume comprises: comparingan extent of audio frames in the buffer of the first zone player to athreshold extent of audio frames; and if the extent of audio frames inthe buffer of the first zone player falls below the threshold extent ofaudio frames, placing one or more additional audio frames into thebuffer to increase the extent of the audio frames in the buffer.
 6. Thefirst zone player of claim 5, wherein retaining the at least some of theaudio frames in the buffer for use during the fast-resume furthercomprises: if the extent of audio frames in the buffer of the first zoneplayer exceeds the threshold extent of audio frames, discarding one ormore of the audio frames in the buffer.
 7. The first zone player ofclaim 1, wherein preparing for the fast-resume of the synchronousplayback of the given audio content further involves: maintainingcryptographic parameters for the audio frames in the buffer that areretained for use during the fast-resume.
 8. The first zone player ofclaim 1, wherein each audio frame in the buffer comprises a respectiveplayback time for the audio frame; wherein the instruction to the secondzone player to cease playback of the given audio content and prepare forthe fast-resume comprises an instruction to discard any audio framesthat are in a buffer of the second zone player; wherein initiating thefast-resume of the synchronous playback of the given audio contentfurther involves: after determining the future resume time, updating theaudio frames that are retained in the buffer of the first zone player byupdating the respective playback times for the audio frames that areretained in the buffer of the first zone player; and transmitting theupdated audio frames in the buffer to the second zone player; andwherein the instruction to the second zone player to resume playback ofthe given audio content at the future resume time comprises aninstruction to use the updated audio frames transmitted to the secondzone player to resume playback of the given audio content at the futureresume time.
 9. The first zone player of claim 1, wherein theinstruction to the second zone player to cease playback of the givenaudio content and prepare for the fast-resume comprises an instructionto retain audio frames that are in a buffer of the second zone player;and wherein the instruction to the second zone player to resume playbackof the given audio content at the future resume time comprises aninstruction to use the audio frames retained in the buffer of the secondzone player to resume playback of the given audio content at the futureresume time.
 10. The first zone player of claim 1, wherein theinstruction to the second zone player to resume playback of the givenaudio content at the future resume time comprises an identification ofthe given audio frame.
 11. A non-transitory computer-readable medium,wherein the non-transitory computer-readable medium is provisioned withprogram instructions that are executable by a first zone player suchthat the first zone player is configured to: engage in synchronousplayback of given audio content as part of a group that includes atleast a second zone player, wherein engaging in the synchronous playbackof given audio content as part of the group involves: obtaining thegiven audio content from an audio source; generating audio frames thatare representative of the given audio content; placing the audio framesinto a buffer of the first zone player; transmitting the audio frames inthe buffer to the second zone player; and using the audio frames in thebuffer to play the given audio content in synchrony with the second zoneplayer; while engaging in the synchronous playback of the given audiocontent as part of the group, receive a command to pause the synchronousplayback of the given audio content; after receiving the command topause the synchronous playback of the given audio content, prepare for afast-resume of the synchronous playback of the given audio content,wherein preparing for the fast-resume of the synchronous playback of thegiven audio content involves: identifying a given audio frame in thebuffer at which to begin the fast-resume; sending an instruction to thesecond zone player to cease playback of the given audio content andprepare for the fast-resume; and ceasing use of the audio frames in thebuffer to play the given audio content while retaining at least some ofthe audio frames in the buffer for use during the fast-resume;thereafter receive a command to resume playback of the given audiocontent; and after receiving the command to resume playback of the givenaudio content, initiate the fast-resume of the synchronous playback ofthe given audio content, wherein initiating the fast-resume of thesynchronous playback of the given audio content involves: determining afuture resume time at which the first and second zone players are toresume the synchronous playback of the given audio content; transmittingan instruction to the second zone player to resume playback of the givenaudio content at the future resume time; and at the future resume time,resuming use of the audio frames in the buffer, starting with the givenaudio frame, to play the given audio content in synchrony with thesecond zone player.
 12. The non-transitory computer-readable medium ofclaim 11, wherein identifying the given audio frame in the buffer atwhich to begin the fast-resume comprises: determining a time within thegiven audio content that corresponds to when the command to pause thesynchronous playback of the given audio content was received; andidentifying whichever audio frame in the buffer corresponds to a timewithin the given audio content that is closest to the determined timewithin the given audio content.
 13. The non-transitory computer-readablemedium of claim 11, wherein identifying the given audio frame in thebuffer at which to begin the fast-resume comprises: identifyingwhichever audio frame in the buffer was scheduled to be played next whenthe command to pause the synchronous playback of the given audio contentwas received.
 14. The non-transitory computer-readable medium of claim11, wherein the at least some of the audio frames that are retained inthe buffer of the first zone player comprise at least the given audioframe and any audio frame in the buffer subsequent to the given audioframe.
 15. The non-transitory computer-readable medium of claim 11,wherein retaining the at least some of the audio frames in the bufferfor use during the fast-resume comprises: comparing an extent of audioframes in the buffer of the first zone player to a threshold extent ofaudio frames; and if the extent of audio frames in the buffer of thefirst zone player falls below the threshold extent of audio frames,placing one or more additional audio frames into the buffer to increasethe extent of the audio frames in the buffer.
 16. The non-transitorycomputer-readable medium of claim 15, wherein retaining the at leastsome of the audio frames in the buffer for use during the fast-resumefurther comprises: if the extent of audio frames in the buffer of thefirst zone player exceeds the threshold extent of audio frames,discarding one or more of the audio frames in the buffer.
 17. Thenon-transitory computer-readable medium of claim 11, wherein preparingfor the fast-resume of the synchronous playback of the given audiocontent further involves: maintaining cryptographic parameters for theaudio frames in the buffer that are retained for use during thefast-resume.
 18. The non-transitory computer-readable medium of claim11, wherein each audio frame in the buffer comprises a respectiveplayback time for the audio frame; wherein the instruction to the secondzone player to cease playback of the given audio content and prepare forthe fast-resume comprises an instruction to discard any audio framesthat are in a buffer of the second zone player; wherein initiating thefast-resume of the synchronous playback of the given audio contentfurther involves: after determining the future resume time, updating theaudio frames that are retained in the buffer of the first zone player byupdating the respective playback times for the audio frames that areretained in the buffer of the first zone player; and transmitting theupdated audio frames in the buffer to the second zone player; andwherein the instruction to the second zone player to resume playback ofthe given audio content at the future resume time comprises aninstruction to use the updated audio frames transmitted to the secondzone player to resume playback of the given audio content at the futureresume time.
 19. The non-transitory computer-readable medium of claim11, wherein the instruction to the second zone player to cease playbackof the given audio content and prepare for the fast-resume comprises aninstruction to retain audio frames that are in a buffer of the secondzone player; and wherein the instruction to the second zone player toresume playback of the given audio content at the future resume timecomprises an instruction to use the audio frames retained in the bufferof the second zone player to resume playback of the given audio contentat the future resume time.
 20. A method carried out by a first zoneplayer, the method comprising: engaging in synchronous playback of givenaudio content as part of a group that includes at least a second zoneplayer, wherein engaging in the synchronous playback of given audiocontent as part of the group involves: obtaining the given audio contentfrom an audio source; generating audio frames that are representative ofthe given audio content; placing the audio frames into a buffer of thefirst zone player; transmitting the audio frames in the buffer to thesecond zone player; and using the audio frames in the buffer to play thegiven audio content in synchrony with the second zone player; whileengaging in the synchronous playback of the given audio content as partof the group, receiving a command to pause the synchronous playback ofthe given audio content; after receiving the command to pause thesynchronous playback of the given audio content, preparing for afast-resume of the synchronous playback of the given audio content,wherein preparing for the fast-resume of the synchronous playback of thegiven audio content involves: identifying a given audio frame in thebuffer at which to begin the fast-resume; sending an instruction to thesecond zone player to cease playback of the given audio content andprepare for the fast-resume; and ceasing use of the audio frames in thebuffer to play the given audio content while retaining at least some ofthe audio frames in the buffer for use during the fast-resume;thereafter receiving a command to resume playback of the given audiocontent; and after receiving the command to resume playback of the givenaudio content, initiating the fast-resume of the synchronous playback ofthe given audio content, wherein initiating the fast-resume of thesynchronous playback of the given audio content involves: determining afuture resume time at which the first and second zone players are toresume the synchronous playback of the given audio content; transmittingan instruction to the second zone player to resume playback of the givenaudio content at the future resume time; and at the future resume time,resuming use of the audio frames in the buffer, starting with the givenaudio frame, to play the given audio content in synchrony with thesecond zone player.